PURPOSE: To form the buffer layer of an Ag single crystal thin film excellent in surface flatness between the artificial metal lattice and a substrate at the time of forming the thin film on the substrate of MgO or Si by ion-beam sputtering by keeping the subtrate at a specified temp.

CONSTITUTION: An ion-beam sputtering system is used to laminate an Ag (100) single crystal film 2 on an Si (100) or MgO (1 00) substrate 1 and an Ag (111) single crystal film on an Si (111) substrate 1. A vacuum chamber 10 is provided with a Kaufmann-type ion source 11, and an Ag target 5 is sputtered. The divergence field of the sputtered particles 5' is limited by a top plate 6, a shutter is opened or closed while monitoring the film thickness by the shutter 7 and quartz-resonator film thickness meter 8 driven from outside the vacuum chamber to keep the substrate at 50-250°C, hence the (100) and (111) silver single crystal thin film excellent in surface flatness is obtained, and an artificial metal lattice having a better characteristic than before is obtained.