Magnetic Properties of PrAl2 and ErAl2

Abstract

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 ErAl₂; 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 T_C 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 T_C of the form M ∝ (T_C‐T)^β, where β=0.6±0.1.