Magnetic anisotropy and spin-reorientation in HoAl 2

Abstract

Torque measurements have been performed at several temperatures and magnetic fields, on a single crystal of HoAl 2 in the (1 1 0) plane. The easy magnetization direction changes from the [1 0 0] to [1 1 0] near T R = 20 K in magnetic fields between 0.2 and 1.6 T. At temperatures below T R a new non-major cubic symmetry easy direction appears which rotates with temperature in the plane of the sample. This behaviour and that of the complete torque curves have been interpreted on the basis of a single ion model.