CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority to U.S. Provisional Application No. 63/218,868, filed July 6, 2021, and U.S. Provisional Application No. 63/252,461, filed October 5, 2021, both of which are incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH AND

DEVELOPMENT

[0002] This invention was made with government support under NSF Cooperative Agreement No. DMR-1157490/1644779 awarded by the National Science Foundation (NSF). The government has certain rights in this invention.

BACKGROUND

[0003] A superconductor is a substance that conducts electricity without electrical resistance when it drops below a given critical transition temperature (T _c ). This temperature varies depending on the composition of the substance itself, as well as other factors, such an amount of pressure that the substance is subjected to. In some cases, however, substances may be associated with extremely low transition temperatures, which may limit the practical applications of the superconductive properties of such substances. The search for room temperature superconductivity has accelerated dramatically in the last few years, and this search has been largely driven by theoretical predictions that first indicated that alloying dense hydrogen with other elements could produce conventional phonon-mediated superconductivity at very high temperatures and at accessible pressures, and, more recently, with the success of structural search methods that have identified specific candidates and pressure-temperature (P-T) conditions for synthesis.

[0004] It is with respect to these and other considerations that the disclosure made herein is presented.

BRIEF DESCRIPTION OF THE DRAWINGS [0005] The detailed description is set forth with reference to the accompanying drawings. The use of the same reference numerals may indicate similar or identical items. Various embodiments may utilize elements and/or components other than those illustrated in the drawings, and some elements and/or components may not be present in various embodiments. Elements and/or components in the figures are not necessarily drawn to scale. Throughout this disclosure, depending on the context, singular and plural terminology may be used interchangeably.

[0006] FIG. 1 depicts an exemplary setup for synthesizing a superhydride superconductor is provided in accordance with the principles of the present disclosure. [0007] FIG. 2 depicts a graph of electrical resistivity associated with a sample, as depicted in FIG. 1, in accordance with the principles of the present disclosure.

[0008] FIG. 3 depicts graphs of electrical resistivity associated with each sample, as depicted in FIG. 1, and of transitions detected in said graphs, in accordance with the principles of the present disclosure.

[0009] FIG. 4 depicts a graph of electrical resistivity associated with a sample, as depicted in FIG. 1, and a graph of corresponding fit lines in accordance with the principles of the present disclosure.

[0010] FIG. 5 depicts a graph illustrating electrical resistivity associated with a sample, as depicted in FIG. 1, in accordance with the principles of the present disclosure.

[0011] FIG. 6 depicts a graph illustrating cool-down traces in various static magnetic fields associated with a sample, as depicted in FIG. 1, in accordance with the principles of the present disclosure.

[0012] FIG. 7 depicts graphs illustrates diffraction patterns associated with a sample, as depicted in FIG. 1, in accordance with the principles of the present disclosure.

[0013] FIG. 8 depicts a graph illustrating diffraction patterns obtained from a central culet area associated with a sample, as depicted in FIG. 1, in accordance with the principles of the present disclosure.

[0014] FIG. 9 depicts a graph illustrating changes in specific volumes of various chemical compositions in accordance with the principles of the present disclosure.

[0015] FIG. 10 depicts X-ray powder diffraction data obtained from a sample, as depicted in FIG. 1, after the final thermal excursion to 580 K in accordance with the principles of the present disclosure.

[0016] FIG. 11 depicts X-ray powder diffraction data obtained from a sample, as depicted in FIG. 1, in accordance with the principles of the present disclosure. [0017] FIG. 12 depicts example DACs in accordance with the principles of the present disclosure.

[0018] FIG. 13 depicts an example DAC in accordance with the principles of the present disclosure.

[0019] FIGS. 14A-B depict images from the focused ion beam processing and from the FIB electrode fabrication on an anvil of a DAC in accordance with the principles of the present disclosure.

[0020] FIG. 15 depicts an image taken through the anvils of a DAC prior to synthesis using X-ray transmission, as detected by a photodiode, in accordance with the principles of the present disclosure.

[0021] FIG. 16 depicts images illustrating electrode configurations associated with a sample, as depicted in FIG. 1, in accordance with the principles of the present disclosure. [0022] FIG. 17 depicts graphs illustrating electrical resistivity of a sample, as depicted in FIG. 1, in accordance with the principles of the present disclosure.

[0023] FIG. 18 depicts graphs illustrating electrical resistivity measurements and a comparison of various four-probe measurements associated with a sample, as depicted in FIG. 1, in accordance with the principles of the present disclosure.

[0024] FIG. 19 depicts a graph illustrating electrical resistivity based on a four-probe measurement of the gasket in accordance with the principles of the present disclosure. [0025] FIG. 20 depicts a micrograph of a DAC in accordance with the principles of the present disclosure.

[0026] FIG. 21 depicts grids of spectra numbers in accordance with the principles of the present disclosure.

[0027] FIG. 22 depicts diffraction patterns associated with a sample, as depicted in FIG. 1, and a comparison between an extrapolation and an artificial intelligence approach for estimating magnetoresistance correction, in accordance with the principles of the present disclosure.

[0028] FIG. 23 depicts image sets illustrating various intensity contours and representative diffraction pattern associated with a sample, as depicted in FIG. 1, in accordance with the principles of the present disclosure.

[0029] FIG. 24 shows an example system for synthesizing a superhydride superconductor in accordance with the disclosure. [0030] FIG. 25 shows a flow chart of an example method of synthesizing a superhydride superconductor in accordance with the principles of the present disclosure.

DETAILED DESCRIPTION

Overview

[0031] This disclosure presents systems, devices, and methods to synthesize a superhydride superconductor.

[0032] In some embodiments, a superhydride superconductor may be associated with an onset superconducting transition temperature above 550 Kelvin (K) (for example, 556 K). To produce such an onset transition temperature, a superconductor may be synthesized initially at a pressure of 180 Gigapascal (GPa) (or another appropriate pressure value) by laser heating a mixture of lanthanum (La) and ammonia borane (NH3BH3), which may act as a hydrogen source and pressure medium, in order to form LaH _x (where x may be 10 or any other number) with a superconducting onset transition temperature of 294 K. In some cases, pure hydrogen may also be used as a pressure medium and/or source. Subsequent thermal excursions to higher temperatures to explore the normal state may result in a chemical reaction that may generate a higher order superhydride. For example, LaFb may be a binary system, but the higher order superhydride produced may be a ternary or quaternary system, LaHXY) via substitution at the La- or H-site. Having a high critical superconducting onset transition temperature of 556 K may support the technological viability of producing a superconducting material at temperatures above room temperature. Having a superconducting material that is capable of operating at or above room temperature may be beneficial for a number of reasons, including at least that it may be used for transmission and storage of electricity and its many end uses, information technology, transportation systems, and magnet technology such as MRI machines and magnets for research and substitution in any system that uses permanent magnets. An additional technical advantage may be that the critical field and critical current for a superconductor having an onset transition temperature of 550 K or higher may be extremely high at room temperature or at up to 375 K, thus making it possible to run magnets, etc. without cooling them. These are just a few non-limiting applications of such a superconducting material. [0033] A lanthanum-based superhydride may thus be initially synthesized by laser heating a sample at 180 GPa, and then subjecting the sample to subsequent thermal cycling to promote the chemical reaction to a higher order system, which can irreversibly shift the onset transition temperature, Tc. to 556 K. X-ray characterization may confirm the formation of a distorted LaHio-based backbone that suggests the formation of ternary or quartemary compounds with substitution at the La- and/or H- sites. In some embodiments, the methods used to produce the above-mentioned superhydride superconductor having an onset transition temperature at 550 K or higher may be described below.

Illustrative Embodiments

[0034] The disclosure will be described more fully hereinafter with reference to the accompanying drawings, in which example embodiments of the disclosure are shown. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the example embodiments set forth herein. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made to various embodiments without departing from the spirit and scope of the present disclosure. Thus, the breadth and scope of the present disclosure should not be limited by any of the above- described example embodiments but should be defined only in accordance with the following claims and their equivalents. The description below has been presented for the purposes of illustration and is not intended to be exhaustive or to be limited to the precise form disclosed. It should be understood that alternate implementations may be used in any combination to form additional hybrid implementations of the present disclosure. For example, any of the functionality described with respect to a particular device/component may be performed by another device/component. Further, while specific device characteristics have been described, embodiments of the disclosure may relate to numerous other device characteristics. Further, although embodiments have been described in language specific to structural features and/or methodological acts, it is to be understood that the disclosure is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as illustrative forms of implementing the embodiments.

[0035] Certain words and phrases are used herein solely for convenience and such words and terms should be interpreted as referring to various objects and actions that are generally understood in various forms and equivalencies by persons of ordinary skill in the art.

[0036] Referring now to FIG. 1 , an exemplary setup 100 for synthesizing a superhydride superconductor is provided. Generally, alloying dense hydrogen with other elements may produce conventional phonon-mediated superconductivity at very high temperatures and at accessible pressures. Such superhydride superconductors may be more successfully synthesized with particular elements and under particular pressure-temperature conditions. For example, placing simple binary hydrides under pressure may yield high critical superconducting transition temperatures ( T _c ) of at least 260 Kelvin (K) in LaHio, which is close to a commonly accepted room temperature threshold of 293 K at pressures approximate to 180 Gigapascals (GPa). As depicted in FIG. 1, a metallic lanthanum-based superhydride may be synthesized from a mixture of lanthanum (La) metal and ammonia borane (NFLBFL), and the metallic lanthanum-based superhydride may have a T _c of 294 K for the highest onset. As the metallic lanthanum-based superhydride is subjected to even higher temperatures, a chemical reaction causes the metallic lanthanum-based superhydride to transform into a ternary or higher order system having an even higher transition temperature. Even before the chemical reaction is completed, the T _c for the highest onset may be elevated from 294 K to 556 K due to the superhydride being of a higher order. [0037] Since the theoretical prediction that atomic metallic hydrogen can be a high T _c Bardeen-Cooper-Schrieffer superconductor at sufficiently high densities, chemical pre compression and crystal structure prediction have been used to forecast the manner in which hydrogen molecules in dense structures may be expected to dissociate at particular pressures and their corresponding critical superconducting T _c values. For example, superconductivity has been discovered in the sulfur hydride system with a T _c of 203 K. Additionally, other hydrides with T _c values that approach room temperatures have been discovered, for example, LaHio, which has a T _c of at least 250 K to 260 K (and up to 282 K with thermal cycling that increases the pressure exerted on the hydride), and even lower values of 227 K to 262 K for related YFk/YFL phases. In some instances, crystalline atomic metallic hydrogen may have a near room temperature (293 K) T _c at 500 GPa and a T _c of 420 K above 3 Terapascals (TPa). In other instances, hydrogen may be capable of acting as a superconducting superfluid at similar pressures. Thus, binary hydrides may have T _c values of up to approximately 293 K at megabar pressures above 40 GPa, with more chemically complex hydride systems, such as ternary and higher order systems) having even higher T _c values. For example, Li2MgH16 may have a Tc value of up to 473 K at pressures nearing 250 GPa. [0038] In order to extend phase diagrams of magnetic field dependence of lanthanum- based superhydries to include magnetic fields approaching 100 Tesla (T), and in order to evaluate lower pressure phases such as LaFk, and in order to develop an improved understanding of how T _c changes in experiments involving the LaHio superhydride that is synthesized using ammonia borane (NH3BH3) as the hydrogen source, metallic or plastic diamond anvil cells (DACs) may be developed for studying superhydrides in direct current (DC) magnetic fields that may be sufficiently small enough to fit into pulsed magnets. In some instances, the DACs may be made of hard, high bulk modulus, highly resistive, and non-magnetic superalloys, such as nickel chromium aluminum (NiCrAl), so as to limit eddy-current heating and ensure mechanical stability of the DACs. This enables the DACs to access temperatures of down to 15 K in pulsed magnetic fields. The DACs may include optical openings for providing a multi-probe environment. Additionally, platinum (Pt) electrodes may be created using focused ion beam (FIB) techniques to perform electrical resistivity measurements of the sample. Synthesizing LaH _x by laser heating at 180 GPa can result in a T _c value of 294 K, and subjecting the sample to subsequent thermal cycling irreversibly shifted the T _c value to higher temperatures above 500 K.

[0039] As depicted in FIG. 1, a first DAC 102 may include a first sample 104 and a first set of Pt electrodes 106, and a second DAC 112 may include a second sample 114 and a second set of Pt electrodes 116. Each of the first DAC 102 and the second DAC 112 may respectively include multiple pairs of Pt electrodes 106 and 116. The first sample 104 and the second sample 114 may be comprised of a mixture of lanthanum and ammonia borane (which functions as the hydrogen source and pressure medium). In some instances, the lanthanum is 99% pure. The number of functioning electrodes in the first set of Pt electrodes 106 and the second set of Pt electrodes 116 may be different. In some instances, the first set of Pt electrodes 106 and the second set of Pt electrodes 116 may be configured to run down the position of the anvils, where they are then connected to copper twisted pairs using epoxy or another connecting agent. In some instances, the first DAC 102 and the second DAC 112 may include a boundary 120 of a metal gasket of the DAC having a cubic boron nitride (cBN) insert, and a perimeter 130 of a culet region in each DAC 102 and 112. In some instances, the first set of Pt electrodes 106 and the second set of Pt electrodes 116 may be configured to be located on one anvil, while the ammonia borane and the gasket may be configured to be located on the other anvil. [0040] In some instances, the first DAC 102 may be loaded at 180 GPa to synthesize LaHio, while the second DAC 112 may be loaded at 160 GPa to synthesize LaH6. It should be noted that the first DAC 102 may be loaded at approximately 180 GPa or another appropriate pressure, while the second DAC 112 may be loaded at approximately 160 GPa or another appropriate pressure. Both the first DAC 102 and the second DAC 112 may be laser-heated by a YAG (Yttrium, Aluminum, and Garnet) laser. For example, a 20 pm diameter laser spot may be rastered across the sample 104 and the sample 114 to promote the dissociation of the ammonia borane into the cBN and the hydrogen, which then reacts with the lanthanum. In some instances, diffraction patterns may be collected over the reacted area after laser heating has occurred. In some instances, the first sample 104 may be configured to receive approximately 45 laser pulses (with 4 or 5 pulses at each of nine points of a 10 pm by 10 pm grid). In such instances, the temperature profile of the laser spot falls to room temperature about 30 pm from the center of the laser spot, so a metal portion of the gasket having an inner diameter of 300 pm may not be heated. Notably, rastering a laser spot on a grid with ammonia borane as a hydrogen source and pressure medium may cause a pressure gradient across the first sample 104 as opposed to using liquid hydrogen, and such a rastering process may not be conducive to a homogeneous growth. This may thus have certain effects, including the multiphase composition, unreacted lanthanum, non-zero resistance, and a resistivity background below the transition temperature. After compression, both the first DAC 102 and the second DAC 112 may present with electrical shorts between the metal gasket and the sets of electrodes 106 and 116 respectively. In certain instances, as depicted in FIG. 1, if the first sample 104 is thicker than the second sample 114, compression may cause the first sample 104 to extrude outside the culet region and come into contact with the first set of Pt electrodes 106 at pressures approaching ambience.

[0041] FIG. 2 depicts a graph 200 of electrical resistivity associated with the first sample 104 depicted in FIG. 1, as measured by four probes. More specifically, the graph 200 depicts the change in electrical resistance of the first sample 104, which is used to synthesize LaHio, during the first cool down trace from 300 K to 230 K using four of the six available electrodes of the first set of electrodes 106. The current used may be 10 mA at 7 Hertz (Hz), the pressure may be 1.8 Megabars (Mbar), the temperature warm-up rate may be 1 K/min, and the temperature cool-down rate may be 1 K/min or 0.5 K/min. Notably, a resistance drop is observed at 294 K with no additional transition observed as temperatures cool to 230 K, the temperature range in which T _c has been previously observed in LaH _x systems. The detected transition at 294 K matches the upper theoretical limit for superconducting transitions in the binary LaHio, and further matches experimental results when LaHio was subjected to multiple temperature excursions that increased pressures and temperatures. There may also be a non-zero resistance observed below the onset transition temperature and a background below the superconducting transition temperature that may be attributed to hydrogen deficiency during the synthesis of the superhydride, a series resistance pathway composed of the 360 K superconductor, impurities, grain boundaries, low temperature superconductors, the non-homogeneous nature of the material that makes up the conductive pathway between various voltage taps, and a non-ideal electrical circuit. It should be further noted that both cool-down curves yielded the same onset transition temperature of 294 K, regardless of the cool-down rate, while the warm-up curve reflected a transition onset of almost 296 K.

[0042] FIG. 3 depicts a graph 300A of electrical resistivity associated with the first sample 104 after the superhydride is synthesized following laser heating. The first sample 104 may include two different electrode configurations and may be subjected to a series of thermal cycles in a magnetic field of 0 T. The increasing temperatures raised the onset of the Tc to even higher temperatures. As depicted in the graph 300 A, temperatures of above 370 K were used to determine corresponding electrical resistivities. The graph 300A depicts the Tc value of 294 K. For the first thermal excursion, the 0 T onset temperature appeared near 357 K for the first sample 104, which involved a two-phase superconductor with a combined Tc (90% / 10%) width of approximately 5 K, as indicated by the intersection of the slopes (which are reflected by the dotted lines). A small impurity phase may be observed below this transition. It should be noted that each trace may utilize a different electrode configuration. In some instances, there may be a strong background to the signal due to a network of series and parallel contributions. In experiments conducted on the second sample 114, which contained unreacted lanthanum, similar electrical resistivity dependence and a non-zero resistance at temperatures as low as 1.9 K may be observed, which may allow for the network of series and parallel contributions to be subtracted out. Some of the background may also be caused by an incomplete transition, which may occur in LaH _x systems. [0043] FIG. 3 further depicts a graph 300B of electricity resistivity associated with the first sample 104 and the second sample 114 at temperatures from 0 K to the 360 K transition. As noted in graph 300B, the first sample 104 may be subject to a pressure of 1.85 Mbar, while the second sample 114 may be subject to a pressure of 1.62 Mbar. The graph 300B depicts a lower transition temperature for the second sample 114 than the first sample 104, which is consistent with the second sample 114 being subject to a lower pressure and fewer pulses than the first sample 104. Because no transition was observed for the second sample 114 between 10 K and 370 K, it may be concluded that no high temperature superhydride was generated from the second sample 114. The graph 300B reflects the superconducting transition due to unreacted lanthanum and/or a lower stoichiometry hydride (e.g., PtH _x ) at temperatures below 15 K, and a superconducting transition at 12.5 K was detected for the first sample 104 and a superconducting transition at 9 K was detected for the second sample 114 that can be attributed to a platinum hydride and/or lanthanum. Notably, the first sample 104 reflects an additional transition at temperatures greater than 365 K, and both the first sample 104 and the second sample 114 have a non-zero resistance down to 1.9 K. In this instance, the resistance of the second sample 114 may be almost 10 times higher than the resistance of the first sample 104 because the second sample 114 is thinner than the first sample 104 and a smaller surface area of the second sample 114 that is in contact with the Pt electrodes. The ability of the electrical circuit to detect superconductor samples may be validated by the detection of transitions below 15 K.

[0044] FIG. 3 further depicts a graph 300C of electrical resistivity associated with the second sample 114 at varying magnetic fields. For example, magnetic fields of 0 T, 0.1 T, 0.3 T, and 0.5 T were applied to the second sample 114 at low temperatures ranging from 2 K to above 8 K. As seen from the graph 300C, three transition points A, B, and C were observed, although they are suppressed by the applied magnetic field.

[0045] FIG. 3 additionally depicts a graph 300D that illustrates the three transitions A, B, and C detected in the graph 300C. The graph 300D illustrates H _C (T) as a function of temperature, and the data associated with the three transitions may be fit using a Ginzburg- Landau formalism, which is further explained below in relation to FIG. 4. While the three resistive transitions do not reach a zero resistance state, the Ginzburg-Landau fit curves make clear that the three resistive transitions are superconducting in nature and validate the electrical circuit. [0046] FIG. 4 depicts a graph 400A that illustrates electrical resistivity for the first sample 104 during each thermal cycle. Each thermal cycle may involve successive cool down and warm-up processes at a different fixed applied magnetic field. For example, as depicted in the graph 400A, the first thermal cycle may involve a 0 T magnetic field, the second thermal cycle may involve a 2 T magnetic field, the third thermal cycle may involve a 10 T magnetic field, and the fourth thermal cycle may involve a 16 T magnetic field. In some instances, a current of 0.6 A may be applied at 7 Hz with temperatures between 290 K and 370 K at a rate of temperature change of 0.2 K/min, with a thermalization time of 30 minutes at 290 K before each warm-up. The first sample 104 was allowed to equilibrate at 370 K for each thermal cycle with minimal increase in electrical resistance, thus indicating the completion of the reaction and pointing to the cool-down traces as being most representative of the stable material within each set of curves. It should be noted that the cool-down traces are indicated by dashed lines, while the warm-up traces are indicated by solid lines. The traces for each thermal cycle are shifted vertically for clarity. In some instances, the magnetoresistance of a thermometer used to measure the temperature may be accounted for.

[0047] As depicted in FIG. 4, T1 indicates an approximate transition onset on cool down traces, while T2 indicates an approximate transition onset on warm-up traces, and T3 indicates a temperature at which hysteresis of the cool-down and warm-up traces closes. T2 may be generally observed to be lower than Tl. This may be due to a lag between the thermometer and the first sample 104, but the hysteresis may be real due to the temperature sweep being at 0.2 K/min and the separation being different for each thermal cycle. This may also be due to the first order nature of the transition or the continuing evolution of the first sample 104 upon successive thermal cycles. Notably, all four thermal cycles collapsed onto one another at temperatures below 315 K. After background subtraction has been performed, a shift of 11 K was observed for T2 and a shift of 19.5 K was observed between magnetic fields of 0 T and 16 T. This shift further demonstrates the superconducting nature of the high-temperature transition. It should be noted that the warm-up traces show additional changes that may reflect a continuing synthesis.

[0048] FIG. 4 depicts a graph 400B that illustrates the evolution of Tl , T2, and T3 points given various magnetic fields and corresponding fit lines for each of Tl, T2, and T3. Assuming that the first sample 104 involves a conventional Bardeen, Cooper, and Schrieffer (BCS) superconductor, fit lines for T1 and T2 may be determined using the Ginzburg- Landau relation: moH,AΊ') = moH ₀ ( 0)(1 - (T/T _c ) ² ). Such an equation may yield a H _c (0 K) of 2.0(5) kiloTeslas (kT) for T1 and 0.4(1) kT for T2, subject to appropriate error margins. In some instances, T3 may be fit using an irreversibility line. In other instances, for a Type II superconductor, T3 may be interpreted as the melting of the vortex glass and may alternatively be fitted by an Almeida-de Thouless equation, where H„ _T = H, _rr ( 0 K)(l - ( ///>,)". where Hirr(0 K) is the irreversibility field of the glass transition at 0 K and To is the transition temperature given zero magnetic field. In this instance, n = 1.5, which is the theoretical value for the exponent for superconductor vortices. It should be noted that when the shift in the superconducting transition for the first sample 104 was re-evaluated in a 41.5 T DC resistive magnet, and all six working electrodes for the first sample 104 were used in order to measure an additional resistance channel simultaneously, similar shifts of the transition to higher temperatures up to 580 K were observed when successive thermal cycles were carried out to higher temperatures in order to establish a clear signature of the normal state. The upper temperature limit of 580 K was due to the stability of structural and electrically conductive epoxies within the first DAC 102 and heating complications.

[0049] FIG. 5 depicts a graph 500 illustrating electrical resistivity associated with the first sample 104 as the first sample 104 undergoes various thermal cycles. The graph 500 may reflect various cool-down traces beginning from various initial maximum temperatures, including 300 K and 370 K maximum temperatures generated by a 16 T magnetic field, and 390 K, 400 K, 410 K, 430 K, 445 K, 503 K, 525 K, 530 K, and 580 K maximum temperatures generated by the 41.5 T DC resistive magnet. Each cool-down trace was obtained using the same set of electrodes and a current of 600 nA. The traces generated by the 16 T magnetic field were collected at 7 Hz, while the cool-down traces generated by the 41.5 T DC resistive magnet were collected at 48.5 Hz to minimize the out-of-phase component. The 41.5 T DC resistive magnet was configured to remain at each maximum temperature for at least thirty minutes to allow the synthesis to stabilize as realized by a steady sample resistance, and then subsequently cooled at a rate of 0.5 K/min. As seen in the graph 500, the onset temperature T _c increases from 295 K to 556 K across thermal cycles, and the transition amplitude increases across each thermal cycle, which is likely due to an ongoing chemical reaction. Similar trends have been observed in superconducting hydrides other than LaHio. It should be noted that the temperature dependence of the resistance in the proposed superconducting state may also be identical for all curves, thus indicating that the various contributions to the background are not affected by the chemical reaction. The non-zero state being attributed to additional unreacted lanthanum between the electrodes. [0050] FIG. 6 depicts a graph 600 illustrating cool-down traces in various static magnetic fields. For example, as depicted in the graph 600, the cool-down traces were generated in static magnetic fields of 40 T, 33 T, 20 T, and 0 T in that order. While temperature sweeps in the various static magnetic fields involved initial maximum temperatures of 400 K, 430 K, 445 K, 503 K, and 530 K, the graph 600 depicts the cool down traces where the initial maximum temperature was 503 K, because the data where the initial maximum temperature was 530 K indicated either an electrical contact degradation or the development of a touch between the cryostat and the magnet, thus adding vibrations in the signal that degraded the signal-to-noise ratio. The temperatures in the magnetic field may be corrected for the magnetoresistance of the platinum thermometer that is used and a quadratic background may be subtracted over the entire temperature range. The difference in a signal-to-noise ratio between the zero-field trace and the applied-field traces arises from vibrations generated by cooling water flowing through the resistive magnet when in operation. The absence of recorded data at temperatures between 470 K and 480 K for the 33 T cool-down trace resulted from software issues. It should be noted that a Ginzburg- Landau function may not be preferable for generating a fit on these data sets due to the evolution of each sample with each thermal cycle. It should further be noted that although the onset of the transition shifts from 492 K at 0 T to 486 K at 40 T, the width of the transition at 0 T, and the additional transitions appearing in the 20 T and 33 T curves make interpreting this data difficult. It should additionally be noted that fixed-field temperature sweeps within a family of curves above 370 K should be avoided due to the incomplete nature of the chemical reaction, as seen from the shift in the transition with each increasing temperature excursion.

[0051] FIG. 7 depicts a graph 700A that illustrates diffraction patterns obtained from a central culet of the second DAC 112 and the surrounding area. In some instances, the diffraction measurements may be performed by a micro-focused, high-energy X-ray beam having a 2 pm x 2 pm focal spot at 42.9 kiloelectron volts (keV) or 0.2887 Ampere (A) and a large focal length. Notably, small opening angles (of approximately 6° Q) both in the incident and exit directions and the insulating, low Z gasket (for example, the cBN insert), and the small amount of the sample both result in the collection and interpretation of 2D diffraction maps being a challenge. For example, 2D maps at 3 pm spatial resolution resulted in over 2500 patterns collected over a 1.5 mm x 1.5 mm area. The identification of the diffraction peaks are further illustrated in graph 700B. The diffraction peaks ascribed to lanthanum (in the R3m phase) are shaded, while the diffraction peaks ascribed to platinum are solidly colored. The expected diffraction peaks from hexagonal LaFh are also indicated by the marker, but the graphs do not show any evidence of its presence or of any of the other lanthanum hydrides below LaHio. It should be noted that the broad diffraction peaks may be attributed to the formation of platinum hydride. [0052] It should also be noted that the second sample 114 was pressurized at 162(5)

GPa and did not couple to the heating laser during synthesis due to the insufficiency of the thermal buffer (particularly at such high pressures). In the case of the second sample 114, the thermal buffer also acted as the hydrogen source, thus resulting in the resistivity measurements indicating a predominance of unreacted lanthanum (having a transition temperature of 5 K).

[0053] FIG. 8 depicts a graph 800 illustrating diffraction patterns obtained from a central culet area of the first DAC 102 at a temperature of 300 K and a pressure of 180 GPa. Electrical resistivity measurements indicate a transition temperature at 294 K that is followed by a monotonic increase in the transition temperature with each cycle of thermal heating and cooling, thus causing a gradual change in the composition of the first sample 104. Diffraction measurements are then made ex-situ at 300 K after the final thermal cycling. The various diffraction phases identified include markers 802 indicating unreacted lanthanum ( Fmmm ), markers 804 indicating platinum ( Fm3m ), markers 806 indicating PtH _x ( Fm3m ), markers 808 indicating LaHio-x ( R3m ), and markers 810 indicating LaHio-x ( Fm3m ). The arrow in the graph 800 refers to a diffused peak that can be attributed to platinum intercalculated with hydrogen. The estimated cell parameters and cell volumes are described as follows:

[0054] Notably, each of the diffraction peaks in the graph 800 do not have the same widths and the mixture of phases with different weights, which indicate different overall chemical compositions, may be used to fit the whole pattern. As described in the table above, five different phases may be identified. The presence of the Fmmm La and Fm3m Pt may be due to unreacted sample and underlying electrodes, while the presence of the Fm3m PtH _x and the Fm3m LaHio-x having smaller peak widths indicate their origin as due to laser heating and reacting with the hydrogen source in close contact. The presence of the rhombohedral R3m LaHio-x is particularly noteworthy due to the complex admixture of this phase with the cubic phase, both of which have similar molar volumes. The graph 800 thus provides the following observations: (1) the cubic and rhombohedral phases ofLaHio-xhave similar unit cell volumes that track close to LaHx. (2) the volumes of Pt and unreacted La track close to expected volumes for 175 GPa, which is the pressure estimated from diamond Raman measured before and after synthesis using 532 nm excitations, and (3) while both the phases of LaHio-x show volumes consistent with lower hydrogen stoichiometry, the volume of PtH _x shows a stoichiometry of PtHs.

[0055] FIG. 9 depicts a graph 900 illustrating changes in specific volumes of various chemical compositions. For example, the graph 900 depicts the specific volumes of Pt, La, LaFh, LaFL, PtFk, LaFk, LaHs, and LaHio at various pressures. The circles depicted in the graph 900 are associated with the first sample 104, while the squares on the graph 900 are associated with the second sample 114. The pressure-volume curves in the graph 900 demonstrate that the apparently lower hydrogen stoichiometry in LaHio-x is not a result of a hydrogen deficiency or an incomplete reaction, but rather a result of substitution of H in either (or both) of the Fm3m and rhombohedral phases by another ligand (for example, Pt and/or BFh). This conclusion may be further verified by recording the diffraction patterns progressively after each thermal cycle in the resistivity measurements. The graph 900 further demonstrates that the first sample 104, which was successfully laser heated at pressures above 170 GPa, shows a distinctly recognizable backbone inStn LaHio-x structure consistent with observed resistivity transition above 260 K in the first cooling cycle. The graph 900 additionally demonstrates that the successive heating cycles for the first sample 104 resulted in gradual chemical changes to this phase that resulted in a complex admixture of Fm3m and rhombohedral LaHio-x having similar volumes, and that the observed synthesis of PtH8 is due to the availability and proximity of the hydrogen source (unreacted ammonia borane) and thermal cycling.

[0056] Although not explicitly depicted in FIGS. 1 -9, it is evident from the experimental results depicted in FIGS. 2-9 that superconductivity has been observed in a lanthanum-based superhydride sample beginning at room temperature that shifts upwards in a controlled fashion with thermal excursions to a value up to 560 K with a notable concomitant increase in the amplitude. The onset temperature may be observed at 294 K, which is consistent with previously observed preliminary observations having an onset transition temperature above 260 K. The initial increase in onset transition temperatures from 294 K to 370 K may be related to the enhancement of transition temperatures on repeated thermal cycling observed in the simpler binary hydride FbSe and described in preliminary reports about the synthesis of superconducting FbS. This explanation, however, may be unlikely, because the maximum predicted transition temperature for the binary LaHio/n system is 288 K. Instead, it may be more likely that the higher onset transition temperatures can be ascribed to additional chemical transformations induced by pressure, shear, temperature, potential magnetic fields, and possibly molten hydrogen (which can exist at room temperature in pressures above 200 GPa).

[0057] In addition to boron and nitrogen from the ammonia borane (the hydrogen source) and/or the composite gasket insert (of cBN) and the carbon from the epoxy binder, C and Ga from the Pt electrodes may also make contact with the LaH system and may react with this binary system to form a ternary or higher system. While the initial laser synthesis may generate the binary system, the thermal excursions may be critical to degrade the epoxy binder in the cBN insert, thus allowing C and possibly H to diffuse into the sample. Further, Pt and Au from the electrodes and the amorphous FIB-ed surface of the diamond may also act as a catalyst or a catalytic bed, respectively, to help form doped alloys or new stoichiometric compounds. Notably, cool-down traces at 294 K and 360 K appear to have only two phases with a third broad phase, which may be due to a disordered phase, while the higher onset temperature transitions have numerous transitions in the warming and cooling traces that support the occurrence of a chemical reaction that is activated with increasing temperatures. Further, thermally optimized ordering of the hydrogen in the system may allow for higher transition temperatures, particularly when accompanied with a reduction in the dimensionality or realization of a more crystalline material. It should be noted that even at 580 K, the reaction may not be complete, and higher temperatures and/or further thermal annealing may be required.

[0058] While the high-temperature transition onsets have the characteristic features of superconductivity, and the X-ray data confirms the presence of both substituted Fm3m and R3m LaHio-x, other interpretations cannot be ruled out in the absence of measurements of the Meissner effect or shifts in the highest transition temperatures with applied magnetic fields. These measurements may be difficult to obtain due to the ongoing chemical transformations taking place during the measurements (for example, the very high He implied by the fit to the existing data). In one example, a transition may have occurred from a low-temperature metal to a high-temperature semi-metal or insulator. However, transitions to insulating states occur with the opening of an energy gap in the Fermi surface, thus leading to an activated behavior in resistivity, which was not observed. In another example, a metal-to-metal phase transition may have occurred. Such a transition could either arise from a magnetic or a structural phase transition. Magnetic phase transitions may be suppressed or smoothed by external magnetic fields, but the sharpening of the onset of the transition at a 41 T magnetic field is observed, and field sweets at fixed temperatures below the transition revealed no anomalies. Additionally, a high-temperature structural phase transition can also be eliminated, because the loading and synthesis for such a transition is similar to another process that resulted in a 260 K superconductor. When room temperature X-ray diffraction was performed after a final 600 K thermal excursion, the data obtained below the transition temperature revealed both Fm3m and R3m LaHio-x structures, where the Fm3m LaHio-x structures are similar to room temperature X-ray powder diffraction data obtained by the other process in the normal state on a binary LaHio superhydride. This may thus eliminate a structural phase transition, Unusual temperature- induced electronic transitions to an insulating state must also be ruled out. [0059] Thermal expansion may also occur at high pressure, and all pressure cells will experience pressure changes as the temperature is varied. Thermal cycles may thus often lead to permanent pressure changes due to mechanical relaxation. For example, the pressure of the first sample 104 was only measured at room temperature after initial synthesis, and then again after the thermal excursions that ultimately generated the 556 K transition. Both measurements revealed a maximum pressure at the center of the culet of the first DAC 102 of 178 GPa, which was subsequently verified by X-ray data. While it may be unclear as to how pressure specifically varies with temperature for the first DAC 102, studies using controlled pressure changes with increases substantially greater than thermal expansion effects have yielded dTc/dp of 1.6 K/GPa for Hgl223, 1 K/GPa for the ternary superhydride C-S-H, and up to 8 K/GPa for optimally doped YBCO. For C-S-H, the initial T _c was about 150 K at 140 GPa, which increased to 288 K at 271 GPa. A two-fold increase in the transition temperature of 260 K was observed, which is difficult to explain with a mechanical change in a DAC that would allow the pressure to increase so much as to account for the doubling of the transition temperature and then return to the same room temperature value after numerous thermal cycles. Notably, all observed transitions were irreversible, and the pressures measured at room temperature during the initial synthesis and six months after the thermal cycles were completed remained the same, thus establishing the occurrence of a chemical reaction rather than temperature-induced pressure changes causing the increased transition temperatures. Additionally, a transition in the metal portion of the gasket in the DAC rather than a transition in the sample may be eliminated because a similar transition was not observed in the second sample 114, where both DACs 102 and 112 have nearly identical circuits and gaskets and are at comparable pressures. The inner diameter of the metal portion of the gasket may be captured between the anvils midway through the second bevel at 300 pm, and the temperature rise experienced by the gasket is negligence at this distance from the location of the laser synthesis according on the culet portion of the DAC.

[0060] However, the transition moves with temperature excursions in an organized fashion from a theoretically predicted and initial and repeatable superconducting transition of 294 K, and the background and non-zero resistance are consistent with experimental results. Thus, the remaining material has a zero resistance at very high temperatures, which demonstrates the superconductivity in the remaining metastable superhydride, although the material may be a still-evolving compound or assemblage. Further, resistance measurements done at various applied magnetic fields at 370 K demonstrated a shift as the magnetic field changed that was compatible with a Ginzburg-Landau fit, thus yielding a H _c (0 K) of about 2000 T for the cool-down traces. When the same transition was tracked in the 41.5 T DC resistive magnet, the transition then irreversibly shifted to higher temperatures with each thermal cycle, with the amplitude of each transition increasing with each excursion. The X-ray powder diffraction data obtained after the maximum thermal cycle up to 600 K further showed the formation of a distorted LaHio-x backbone having a volume reduction of approximately 5% that points to the incorporation of one or more elements or ligands that formed the higher-order hydride. Additionally, the non-zero background is common in other superhydrides, but may be caused by impurities, unreacted host elements, and possible grain boundaries found in the region between the electrodes. Such a non-zero background may be found throughout the various thermal cycles and may be completely field-independent. The X-ray powder diffraction patterns in close proximity to the voltage lead tips further shows both phases involving LaHio-x and also PtH _x and unreacted lanthanum and platinum. Neither the X-ray data nor the resistivity data revealed any evidence of any binary LaH _x , where x < 10. Thus, the portion of the sample having the very high superconducting transition is electrically in series with these other phases, which further explains the lack of a zero-resistance state. Additionally, the field dependence of the transitions below 15 K found in the second DAC 112 reveals Ginzburg-Landau behavior, where the multi-phase transitions below 8 K are most likely due to element lanthanum at different pressures due to being smeared out over the culet region and the bevels, thus confirming that the megabar electrical circuit detected superconducting transitions. The X- ray powder diffraction thus supports the presence of a substituted LaH _x superhydride superconductor. No transitions that would be associated with an LaH _x structure close to x = 8 were observed in the X-ray data, so a higher order superhydride with a T _c onset of 556 K must have been synthesized.

[0061] Further, although not depicted in FIGS. 1-9, the piston-cylinder DACs may be 9.5 mm by 39 mm long, and they may be made from HIPed NiCrAl so as to reduce vibrations and eddy current heating due to changes in magnetic field over time, which may be on the order of dB/dt = 10,000 T/s to 20,000 T/s in pulsed magnetic fields. The DACs may also include a 72 pm culet, and double bevel (8” x 250 pm and 15” x 350 pm) standard anvils with a 3.75 mm girdle. In order to prepare robust conductive leads, a dual beam focused ion beam system may be applied in combination with a scanning electron microscope. A metalorganic gas, such as Trimethyl(methylcylopentadienyl)Platinum(IV), may be injected into the high-vacuum sample chamber via the nozzle of a gas injection system. The focused ion stream may decompose the molecules and precisely deposit platinum that is rich in carbon and gallium (typically at 30% and 10%-20% respectively) onto the anvils. In the same process, the surface of the diamond of the DACs may be amorphized to a depth of approximately 20 nm (for 30 keV gallium ions), thus allowing the carbon-rich platinum deposit to chemically connect with the broken carbon bonds of the diamond. This chemical bonding thus allows the mechanical adhesion of FIB-deposits to the diamond, which makes it robust against mechanical forces, although the high carbon content may reduce the conductivity of such leads by a few Ohms/pm depending on the deposition conditions and the thickness of the layer.

[0062] In order to realize ohmic lead resistance that is deposited, a second step after a transfer to an external sputter deposition system may involve an adhesion layer of titanium and another layer of pure gold being placed on top of the prepared platinum ribbons, with Kapton tape being used to protect the diamond surface against Au deposition. The layer of pure gold may be approximately 100 nm thick. In a third step, the high-current gallium beam may be used to etch away excess gold until the amorphous diamond surface is recovered between adjacent tape. The platinum-gold ribbons may then be covered with an additional FIB-platinum protection layer of approximately 1 pm running alongside the pavilion up to the culet. A last step may involve thin FIB-platinum ribbons having approximately 1 pm thickness being deposited close to the central part of the culet, thus extending the platinum-gold-platinum leads into the sample space, which has a diameter of approximately 40 pm.

[0063] The gaskets may be 135 pm gaskets that are located on the piston anvil and may be indented to a pressure of 15 GPa in a dummy DAC with the same anvil geometry as the first DAC 102 and the second DAC 112 so as to prevent damage to the electrodes while still providing a gasket that mirrors the anvil shape in these DACs. The gaskets may have been removed and laser cut to a diameter halfway through the second bevel, polished to remove burrs and most of the extruded region, and the repositioned in the dummy DAC and filled with a dry mixture of cBN powder and epoxy (10% by weight). The gasket may then be pressed to a load of 25 GPa after which it is laser drilled to a diameter of 40 pm. This composite gasket may then be moved to the piston of the DAC to be used in the experiment. The piston with the gasket secured in a crown may be brought into a flowing argon-filled glove box having an oxygen and water content of less than 1 ppm, where the gasket hole is filled with ammonia borane as the hydrogen source and pressure medium. The gasket and the gasket crown on the piston may thus be electrically isolated from the rest of the DAC. The pressure measurements required for each step in the gasket fabrication may be performed at room temperature using the Raman edge of stressed diamond. A third DAC may be used to mechanically thin and shear a piece of 99% lanthanum to expose clean metal. A schmear of the metal, approximately 2-3 pm thick, may be extracted from this film and placed on a plastic transfer piston, after which it is brought into the glovebox and pushed against the anvil with FIBed electrodes to form a cold weld. The same plastic transfer anvil may be used to initially align this anvil during the assembly of the DAC and the visible impression that remains of that anvil’s culet assists in ensuring that the lanthanum is positioned over the electrodes in the second step. In order to prevent a reaction between lanthanum and air, the sample may be loaded into the DAC and sealed within 30 minutes of extracting the 3-6 pm samples from the freshly exposed metal.

[0064] The assembled DAC may then be taken to the desired pressure for synthesis using the Raman edge of the stressed diamond. Laser synthesis may be performed at an X- ray light source, and X-ray powder diffraction analysis of the results may be attempted following synthesis. The sample heating may be single-sided and may use a fiber laser operating in modulation mode to provide a single square pulse having a total power of 100 W. Temperature measurements may be obtained from a 4-micron area in the center of the heating spot. The laser focal size may be 20 pm2 and the modulation pulse width may be 30 ms. Heating from the laser spot may be negligible beyond 30 pm from the spot center. The upstream side of the DAC may have a 11.5° opening in the piston, while the downstream side may have a 14° opening in the endcap that supports the anvil with electrodes.

[0065] For experiments conducted using a 41.5 T DC resistive magnet, fixed magnetic fields may be applied using consistent sweep rates of 0.5 K/min to 3 K/min for various temperatures. A custom cryostat with a variable temperature insert may provide the sample environment. Each sample may be run under a vacuum with a helium partial pressure of 10 ⁶ Mbar. A small bobbin with three 50 Ohm wire wound heaters in intimate contact with the DAC may be mummified in two layers of 12 mih copper fail and 37 layers of superinsulation. A platinum thermometer may be located within the body of the DAC and may be in intimate mechanical contact with the spring and piston. The thermometer may be used for both control and sensing, although the maximum temperature that can be measured by the thermometer may be limited due to the epoxy that is used to form electrical connections between the twisted pairs and the FIBed electrodes may have a maximum operating temperature of 573 K and may begin to degrade at that point. Further, the epoxy used to fix the twisted pairs in the DAC may have a maximum operating temperature of 390 K and may be completely calcinated after the series of high temperature measurements. [0066] FIG. 10 depicts X-ray powder diffraction data 1000 obtained from the first sample 104 after the final thermal excursion to 580 K. Each spectrum may be separated by 3 microns. Laser synthesis may be performed on a 10 pm x 10 pm grid with a spot-size of 20 pm. Three different zones may be observed in the X-ray powder diffraction data 1000, thus indicating that the laser heating spots can be resolved, which verifies the granular and inhomogeneous growth that results from using ammonia borane as a hydrogen source and laser heating done on a grid. Thus, it is clear that the voltage taps would sample not only the portion of the sample with the high superconducting transition, but also off- stoichiometric bits, unreacted lanthanum, and grain boundaries that give rise to the broad- non-zero resistance that is observed and the metastable, multi-phase material that results in a broad transition.

[0067] FIG. 11 depicts X-ray powder diffraction data 1100 obtained from the first sample 104 in the middle of the culet of the first DAC 102 between the electrodes. The X- ray powder diffraction data 1100 revealed spectra that show that only a small portion of the first sample 104 between the electrodes converted, while a portion of the sample did not reveal any X-ray signal, thus indicating that the first sample 104 is highly inhomogeneous. [0068] FIG. 12 depicts example DACs 1200 in accordance with the disclosure. The DACs 1200 may include a 0.38 mm DAC 1202, a DAC 1204 that is similar to the first DAC 102, and a dis-assembled DAC 1206 with a piston diameter that is 5.38 mm and a total DAC weight of 12.88 grams. The DACs 1200 may be made of plastic, with no metal components except for the electrodes, the electrical leads and contacts, and the sample, so as to minimize eddy current heating in a high pulsed magnetic field environment. The diamond culets are often less than 70 mih, and so the load necessary to generate the 1 Mbar to 2 Mbar pressures for superhydride synthesis may be relatively small. The DACs 1200 may be rotated at He- 3 temperatures in pulsed magnetic fields.

[0069] FIG. 13 depicts an example DAC 1300 in accordance with the disclosure. In some instances, the metal parts of the DAC 1300 may be made of Pascalloy (NiCrAl, or nickel chromium aluminum). The anvil with FIBed electrodes may be attached to the endcap 1302, while another anvil is attached to a piston that may be spring-loaded. A gasket and a gasket table epoxied to the piston may be electrically isolated from the piston and the rest of the DAC 1300. Both anvils may be secured using epoxy. The piece 1304 may have three tabs that register with mating half-cylinders in the body of the DAC 103 to prevent the load unit 1306 from spinning the piston anvil when the load is increased so as to prevent damage to the sample, electrodes, or anvils. An adaptor tube 1308 and a platinum temperature sensor 1310 may be further disposed inside a spring of the DAC 1300.

[0070] FIG. 14A depicts images from the focused ion beam processing in accordance with the disclosure. An image 1402A depicts the Kapton tape used to mask a stone prior to gold sputtering. An image 1402B depicts the resulting AuPt overlay that has been defined with the gallium. An image 1402C depicts the eight electrodes with tabs on top of one of the culets.

[0071] FIG. 14B further depicts images of the FIB electrode fabrication on one of the anvils in a DAC in accordance with the disclosure. An image 1402B depicts a close-up of the platinum-gold-platinum electrodes, in which an overlay defines the edge of the 72 pm culet. The small tabs grown from the main electrodes may encompass a 13 pm circle. An image 1404B depicts the electrodes draped over the bevels and extending down the pavilion, where they are attached to the copper twisted pairs with epoxy.

[0072] FIG. 15 depicts an image 1500 taken through the anvils of the first DAC 102 prior to the synthesis using X-ray transmission detected by a photodiode. The image 1500 clearly depicts the platinum-gold-platinum electrodes in the lighter portions of the image 1500. The letters, A, B, C, and D, which are indicated on the image 1500, indicate the electrode pairs. The spots 1 through 9, which are indicated on the image 1500, indicate the location of laser heating. The laser spot size may be 20 pm in diameter. The laser may be rastered in a 10 pm x 10 pm grid between spots 1 to 9, starting at 20% (i.e., 41.5 Watts) of maximum laser power, which is then increased in 5% increments up to 70% of maximum laser power, or until coupling is observed between the laser and the sample to produce a temperature in the range of 1200 K. This coupling may be characterized by a flash in the visual image of the sample and the temperature measured at the sample by a black body fit of the signal. The laser may be pulsed 4 to 5 times at each spot.

[0073] FIG. 16 depicts an image 1600A illustrating a first electrode configuration for the first DAC 102 used for a 294 K transition temperature measurement. FIG. 16 further depicts an image 1600B illustrating a first channel of the second electrode configuration. Both the first channel and the second channel may be observed when the first DAC 102 is placed in the 41.5 T DC resistive magnet. FIG. 16 additionally depicts an image 1600C illustrating an electrode configuration for the second DAC 112. The first 8° bevel may have a 200 pm outer edge, which may be flat at these pressures, and the central area 1602C may indicate the perimeter of the 72 pm culet, in which all diffraction data is collected.

[0074] FIG. 17 depicts a graph 1700 A that illustrates electrical resistivity of the first DAC 102 having a second electrode configuration. The DAC 102 may be placed in a 41.5 T DC resistive magnet in order to generate cool-down traces involving temperatures of 390 K, 400 K, 410 K, 430 K, 445 K, 503 K, 525 K, 530 K, and 580 K. It should be noted that the graph 1700A depicts results obtained at a 0 T magnetic field at a second channel of the first DAC 102, and that these results reproduce the results obtained in the first channel of the first DAC 102. Notably, heater complications during the 580 K cool-down trace prevented the obtaining of data between 520 K and room temperature for that cool-down trace. However, the resistance of the first sample 104 at 300 K was the same as the resistance for the other curves.

[0075] FIG. 17 further depicts a graph 1700B that illustrates electrical resistivity measurements for in-field cool-down traces for the family of curves for the first DAC 102 at an initial temperature of 503 K. Cool-down traces may involve varying static magnetic fields of 40 T, 33 T, 20 T, and 0 T measured in that order. The temperatures in the field may be corrected for the magnetoresistance of the platinum thermometer that is mechanically anchored to the interior of the first DAC 102, and a quadratic fit to the background may be subtracted. The difference in the signal-to-noise ratio between the zero- field and the applied-field traces may arise from the vibrations generated by the cooling water flowing through the 41.5 T DC resistive magnet when in operation. The 0 T trace may be recorded overnight and without the cooling water fooling. While the onset of the transition may shift from 492 K at 0 T to 486 K at 40 T, the width of the transition at 0 T and the additional transitions appearing in the 20 T and 33 T curves hamper the interpretation. The incomplete nature of the chemical transformation additionally precludes fixed-field temperature sweeps within any family of curves above 370 K. The shift in the transition with each increasing thermal excursion and its multi-phase nature suggests that the material may still be evolving.

[0076] FIG. 18 depicts a graph 1800A that illustrates electrical resistivity measurements for cool-down traces at an initial starting temperature of 503 K for the first DAC 102 in various magnetic fields. The cool-down traces may be measured at constant magnetic fields of 40 T, 33 T, 20 T, and then 0 T in that order. The graph 1800A replicates the results obtained at the first channel of the first DAC 102. The noise levels may be caused by vibrations from water flow in the magnet. The 0 T traces may be carried out with the magnet and the water cooling systems being turned off.

[0077] FIG. 18 further depicts a graph 1800B that illustrates a comparison of various four-probe measurements for the first DAC 102 for the electrode pairs taken after the 580 K temperature excursion. Notably, electrode pair C is the open pair that only measures the gasket and the short between the leads caused by residual gold caused by the sputtering or amorphous carbon generated when the FIBed electrodes are further defined by FIBing that cuts into the diamond anvil. However, electrode pair C demonstrates strong insulating behavior below 20 K and an increase in resistance from 120 W at room temperature to 1E6 W at 2 K. Electrode pairs A, B, and D may exhibit superconducting transitions below 15 K with the slope for all curves in the normal state being comparable. The largest contribution to the background at temperatures above 15 K is from the gasket. Electrode pair B further shows one strong superconducting transition at 10.6 K, which is also observed at 11 K for electrode pair A and at 11.15 K for electrode pair D. These transitions are most likely due to platinum hydride that is also observed in the X-ray data. A superconducting transition of elemental lanthanum may be ruled out due to such onset transition temperatures would indicate a pressure well below 1 GPa. Such transitions may also be due to lower stoichiometry lanthanum superhydrides, with the difference in onset transition temperatures between the electrode pairs being due to compositional variations following an inhomogeneous synthesis, and/or the gradient of pressure across the culet. The transitions between 3 K and 4 K may be attributed to elemental lanthanum captured between the bevels and/or unreacted lanthanum on the culet.

[0078] FIG. 19 depicts a graph 1900 that illustrates electrical resistivity based on a four- probe measurement of the gasket to rule out any transition originating from the gasket and to determine the background contributed by the short to the gasket. A four-probe electrical transport measurement at 0 T and an ambient pressure of a 135 pm strip of the gasket was made. The detected kick around 300 K may be due to a change in the temperature sensor used when detecting higher temperature ranges.

[0079] FIG. 20 depicts a micrograph 2000 of the first DAC 102. The pressure is measured using the Raman edge of a diamond vibron and a 532 nm laser, and the spots 1 through 5 may indicate the positions where the pressure was measured. At spot 1, the detected pressure was 168 GPa, and it indicated a 5 GPa gradient of pressure across the culet. At spot 2, the detected pressure was 173 GPa. At spots 3 and 4, the detected pressures were 178 GPa. At spot 5, the detected pressure was 150 GPa. The spot 5 is located in the bevel region and on the lanthanum, and it was not laser heated. Spot 3 may be measured at the center of the culet of the first DAC 102, and the detected pressure of 178 GPa is consistent with initial measurements and previous derivations.

[0080] FIG. 21 depicts a first grid of spectra numbers 2100A obtained for the first DAC 102 and a second grid of spectra numbers 2100B obtained for the second DAC 112 using electrode pairs A and B.

[0081] FIG. 22 depicts diffraction patterns 2200A recorded while moving away from a point showing predominantly cubic and rhombohedral LaHlO-x in the sample. The sampling may be coarsened (i.e., compared to the step used while recording the data by performing a 3 -point boxcar averaging process). The diffraction patterns 2200 A thus demonstrate that synthesis clearly occurred in localized regions in the sample. FIG. 22 further depicts a comparison 2200B between an extrapolation and an artificial intelligence approach for estimating magnetoresistance correction. Notably, both approaches yield the same result to within 0.15 K at temperatures of 480 K.

[0082] FIG. 23 depicts in image set 2300A an intensity contour of a platinum(lll) diffraction peak and a representative diffraction pattern. The limits may be relaxed to account for a systematic shift in the diffraction peak with varying pressure while ensuring that the accompanying lanthanum diffraction peak is not added in the integrated intensity. The electrodes and the central culet may be discemable. The axes may be labelled in terms of the displacement from the starting point of the x-y scan, where each step is 3 pm in both directions. FIG. 23 further depicts in an image set 2300B a similar intensity contour obtained when the integration is over the lanthanum diffraction peak. However, in this instance, the cross-talk from neighboring LaHio and Pt diffraction peaks cannot be avoided effectively. Notably, the spread of lanthanum may be substantial and not confined to the culet. FIG. 23 additionally in an image set 2300C an intensity contour obtained when the first observed diffraction peak from LaHio-x (both rhombohedral and cubic) is chosen). The overall disposition of the peak around the culet area which was heated during the synthesis is evident.

[0083] FIG. 24 shows an example system 2400 for synthesizing a superhydride superconductor in accordance with the disclosure. The system 2400 may include a first sample chamber 2402 and a second sample chamber 2404. The first sample chamber 2402 may contain a first DAC loaded with a first sample at a first pressure. The second sample chamber 2404 may contain a second DAC loaded with a second DAC loaded with a second sample at a second pressure. The first sample and the second sample may include a mixture of lanthanum (La) and ammonia borane (NH3BH3). The first DAC and the second DAC may be sealed. The system 2400 may further include a pulsed YAG laser 2406 configured to laser heat the first DAC and/or the second DAC to synthesize a superhydride superconductor. In some embodiments, the system 2400 may additionally include a focused ion beam system 2408 configured to create electrodes on a first diamond anvil of the first DAC and/or a second diamond anvil of the second DAC.

[0084] FIG. 25 shows a flow chart 2500 of an example method of synthesizing a superhydride superconductor in accordance with the disclosure. The flow chart 2500 illustrates a sequence of operations that can be implemented in hardware, software, or a combination thereof, such as a magnetometer in accordance with the present disclosure. In the context of software, the operations represent computer-executable instructions stored on one or more non-transitory computer-readable media such as a memory, that, when executed by one or more processors, perform the recited operations. Generally, computer-executable instructions include routines, programs, objects, components, data structures, and the like that perform particular functions or implement particular abstract data types. The order in which the operations are described is not intended to be construed as a limitation, and any number of the described operations may be carried out in a different order, omitted, combined in any order, and/or carried out in parallel. Some or all of the operations described in the flow chart 2500 may be carried out either independently or in cooperation with other devices such as, for example, a computer.

[0085] At block 2505, a first diamond anvil cell (DAC) may be loaded with a first sample at a first pressure. In some embodiments, the first pressure may be 180 Gigapascals (GPa). At block 2510, a second DAC may be loaded with a second sample at a second pressure. In some embodiments, the first sample and the second sample may include a mixture of lanthanum (La) and ammonia borane (NH3BH3). In some embodiments, the second pressure may be 160 GPa. In some embodiments, the first DAC and the second DAC may each be made of a highly-resistive and non-magnetic superalloy configured to limit eddy-current heating. At block 2515, the first DAC and the second DAC may be sealed. At block 2520, the first DAC and/or the second DAC may be laser heated, wherein the laser heating of the first DAC and/or the second DAC synthesizes a superhydride superconductor. In some embodiments, the laser heating may be performed by pulsed YAG lasers. In some embodiments, the superhydride superconductor may be one of a binary superhydride, a quartemary superhydride, a ternary superhydride, a higher order superhydride, or a doped superhydride. In some embodiments, the laser heating of the first DAC and/or the second DAC may include the application of a square single pulse having a total power of 100 Watts via a laser system to the first DAC and/or the second DAC. In some embodiments, focused ion beam systems may be used to create electrodes on a first diamond anvil of the first DAC and/or a second diamond anvil of the second DAC.

[0086] Although specific embodiments of the disclosure have been described, one of ordinary skill in the art will recognize that numerous other modifications and alternative embodiments are within the scope of the disclosure. For example, any of the functionality and/or processing capabilities described with respect to a particular device or component may be performed by any other device or component. Further, while various illustrative implementations and architectures have been described in accordance with embodiments of the disclosure, one of ordinary skill in the art will appreciate that numerous other modifications to the illustrative implementations and architectures described herein are also within the scope of this disclosure. [0087] Certain aspects of the disclosure are described above with reference to block and flow diagrams of systems, methods, apparatuses, and/or computer program products according to example embodiments. It will be understood that one or more blocks of the block diagrams and flow diagrams, and combinations of blocks in the block diagrams and the flow diagrams, respectively, may be implemented by execution of computer-executable program instructions. Likewise, some blocks of the block diagrams and flow diagrams may not necessarily need to be performed in the order presented, or may not necessarily need to be performed at all, according to some embodiments. Further, additional components and/or operations beyond those depicted in blocks of the block and/or flow diagrams may be present in certain embodiments.

[0088] Accordingly, blocks of the block diagrams and flow diagrams support combinations of means for performing the specified functions, combinations of elements or steps for performing the specified functions, and program instruction means for performing the specified functions. It will also be understood that each block of the block diagrams and flow diagrams, and combinations of blocks in the block diagrams and flow diagrams, may be implemented by special-purpose, hardware-based computer systems that perform the specified functions, elements or steps, or combinations of special-purpose hardware and computer instructions.

[0089] Although embodiments have been described in language specific to structural features and/or methodological acts, it is to be understood that the disclosure is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as illustrative forms of implementing the embodiments. Conditional language, such as, among others, “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments could include, while other embodiments do not include, certain features, elements, and/or steps. Thus, such conditional language is not generally intended to imply that features, elements, and/or steps are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without user input or prompting, whether these features, elements, and/or steps are included or are to be performed in any particular embodiment.