PURPOSE: To enable the much magnetoresistance effect making the most of the large magnetic moment of rare earth element to be gained by utilizing the resistance fluctuation of the rare earth element compound wherein the magnetic interaction between rare earth atoms are flustrated.

CONSTITUTION: A magnetic field is detected by the resistance of rare earth element compound wherein the magnetic interaction between rare earth atoms are fluctuated. At this time, the resistance fluctuation of rare earth element compound containing exceeding 20 atomic % of rare earth elements such as Ce, Pr, Cr, Mu, Cu, Au, etc., is utilized. In order to read out the resistance fluctuation, you have only to provide a pair of electrodes for checking the fluctuation in electric resistance by external magnetic field when the electrodes are fed with a current. Through these procedures, much magnetoresistance effect (MR effect) can be gained.