Field-Dependent Magnetic Phase Transitions in Mixed-Valent TmSe

Abstract

A neutron diffraction study of the field-dependent magnetic ordering in TmSe is reported. The magnetic strucutre in zero field is antiferromagnetic fcc type I with $T_{\mathrm{N}}=3.2\mathrm{}$ K. The magnetic phase diagram may be understood as a successive domain reorientation and metamagnetic transitions for $T<\mathrm{}3\mathrm{}$ K with increasing field. We can explain this quantitatively using a simple classical spin Hamiltonian. The mixed-valent character manifests itself mainly in a reduced moment and in a markedly altered crystal field.