MAGNETIC-PROPERTIES OF RARE EARTH COPPER RCUX COMPOUNDS WITH CECU6-TYPE AND AUBE5-TYPE CRYSTAL-STRUCTURES

The magnetic properties of rare earth-copper compounds RCux have been measured in the temperature range 4.2-200 K at a constant applied field of 1 kOe. The compounds have an orthorhombic crystal structure of the CeCu6 type for R = Y, Pr, Nd, Sm, Gd and a cubic crystal structure isostructural with AuBe5 for R = Tb, Dy, Ho, Er, Tm. The susceptibility of the compounds YCu6, LaCu6 and SmCu6 is a very weak function of temperature and these materials do not exhibit any important macroscopic magnetic properties. The high temperature susceptibility of all other RCux compounds follows the Curie-Weiss law with effective moments close to those of the trivalent rare earth ions. The compounds PrCu6 and NdCu6 show a deviation from the Curie-Weiss law below 10 K, their Curie paramagnetic temperatures (CPT) being negative. The ordering temperatures of GdCu6, TbCu5 and DyCu5 lie between 4.2 and 13 K. HoCu5 ErCu5 and TmCu5 show a deviation from Curie-Weiss behaviour below 10 K, their CPT being positive. Metamagnetic behaviour was observed in DyCu5 at 4.2 K in applied fields of 1-20 kOe. © 1979.