MAGNETIC CHARACTERISTICS OF CEAL3 AND CEAL4

The magnetic properties of hexagonal CeAl3 and orthorhombic CeAl4 between 2.2 and 300°K are reported and discussed in detail. Both of these compounds exhibited deviations from Curie-Weiss behavior at low temperatures. These deviations are attributed to a combination of crystal field and exchange interactions. Detailed crystal field calculations are presented for CeAl3 which indicate an overall splitting of 280°K. These calculations take into account the compressed nature of the hexagonal lattice in CeAl3, a feature which introduces a second order term into the crystalline potential. Using this model and making suitable allowances for exchange interactions, it is possible to compute the susceptibility from Van Vleck's equation. The computed and experimental curves agree within 1 per cent over the entire temperature range. Detailed calculations for CeAl4 are not possible at present because of uncertainties in the crystal symmetry; however, the saturation moment of this compound can be attributed to a large crystal field interaction which leaves only the low lying Kramer's appreciably populated below the transition temperature. © 1968.