Metamagnetism of Some Rare-Earth Copper Compounds with CeCu2 Structure

Abstract

Magnetic moments of the series of rare‐earth copper (RCu₂) intermetallic compounds have been measured at temperatures from 1.4° to 300°K. These compounds have an orthorhombic crystal structure and are isostructural with CeCu₂. The susceptibility at high temperatures of most of the compounds followed the Curie—Weiss law giving effective moments close to those of the trivalent rare‐earth ions. Eu and Yb appeared to be divalent. At low fields antiferromagnetic behavior was indicated in some of these compounds by peaks in the curves of moment vs temperature, and by a lack of remanence. Metamagnetic behavior was observed when measurements were made at 4.2°K and with fields up to 80 000 Oe. For example, the moment of TbCu₂ increased abruptly at a critical field, and at 80 000 Oe, although not yet saturated, had a moment of 6.2 Bohr magnetons. The moments of EuCu₂ and GdCu₂ increased gradually, and at 80 000 Oe reached moments of 5.7 and 6.0 Bohr magnetons, respectively. These results indicate a relatively weak antiferromagnetic exchange interaction in these compounds.