Induced-moment ferromagnetic ordering in the singlet-ground state compound TmNi 2

Abstract

We present measurements of the magnetization in very high fields, the low temperature specific heat and the AC susceptibility, both in zero and nonzero magnetic field, of the intermetallic cubic Laves phase compound TmNi 2. This material appears to be a singlet-singlet system with an inter-ionic exchange which just exceeds the critical value for magnetic ordering. The absence of a clear anomaly in the specific heat near the ferromagnetic transition temperature T c = 1.1 K is discussed in a molecular field approximation including crystal field effects. The results of the experiments can qualitatively be described in terms of a set of crystal field parameters corresponding to a Hamiltonian for a system with a distortion from cubic symmetry.