On crystal-field spectroscopy based on specific heat and thermal expansion measurements: application to the TmCu₂intermetallic compound

Abstract

An experimental study based on specific heat, thermal expansion, magnetisation and neutron diffraction measurements on polycrystal and single crystal of the orthorhombic TmCu2 compound is presented. The results are satisfactorily interpreted within a model involving the crystal and molecular field acting on the Tm3+ ions. The energy spectrum of the ground-state multiple 3H6 of Tm3+ with the isolated split lowest quasi-doublet ( Delta 1=5+or-1 K, Delta 2=68+or-3 K) is proposed. The appropriate sets of crystal-field parameters Vlm are obtained and discussed.