UC Irvine

Magnetic-susceptibility and magnetization measurements on single crystals of the CuO2-planar compound Gd2CuO4 indicate copper moment ordering near 260 K, producing an internal field at the gadolinium site that induces substantial anisotropy in the magnetic response. Dilute substitutions for gadolinium and copper leave the essential physics unaffected. We suggest that copper ordering also occurs in Eu2CuO4 on the basis of substitutional studies but is not detected in other rare-earth-based compounds in this series. Rare-earth size appears to play an important role. © 1989 The American Physical Society.