Pressure Dependence of the Magnetic Properties of Mixed-Valence TmSe

Abstract

Measurements of the magnetic moment of TmSe show that the low-field susceptibility and the multiboundary field-temperature (${H}_{0}\ensuremath{-}T$) phase diagram at low temperatures depend strongly on hydrostatic pressure. For ${\stackrel{\ensuremath{\rightarrow}}{\mathrm{H}}}_{0}\ensuremath{\parallel}[100]$ the upper transition fields increase at a rate \ensuremath{\simeq} + 1.7 kG/kbar. The magnetic properties reflect the valence changes of ${\mathrm{Tm}}^{2+}$ to ${\mathrm{Tm}}^{3+}$ as the lattice contracts, and for $P\ensuremath{\gtrsim}20$ kbar, the Tm ion should be trivalent.