MAGNETIC PROPERTIES OF PRAL2 AND ERAL2

The magnetic properties of PrAl2 and ErAl2 have been investigated by neutron-diffraction and susceptibility measurements on powder samples of the above compounds. The susceptibility data show that both compounds obey the Curie-Weiss law; the effective moment per molecule in the paramagnetic region is 3.5±0.05 μB for PrAl2 and 9.2±0.1 μB for ErAl2. The neutron-diffraction measurements confirm that these compounds are ferromagnetically ordered below a Curie temperature of 34°K for PrAl2 and 14°K for ErAl 2; the respective saturated ordered moments at the rare earth atom sites are 2.94±0.05 μB and 8.3±0.3 μB. The magnetic form factor data from the ErAl2 coherent magnetic reflections are in good agreement with similar data obtained by other investigators on an Er single crystal. The magnetic scattering intensity of the (111) reflection from PrAl2 was measured just below the Curie temperature TC in order to determine the long-range magnetic-order temperature dependence. The results show that the spontaneous magnetization M follows a power law in the vicinity of TC of the form M ∝ (TC-T)β, where β=0.6±0.1. © 1968 The American Institute of Physics.