NMR, high frequency EPR and magnetization studies of YF3:Tm 3+ and TmF3

Abstract

Magnetic properties of single crystal and powder samples of thulium fluoride, TmF3 (orthorhombic Pnma space group), and single crystals of YF3 doped with the Tm3+ ions are studied by NMR, high-frequency EPR and dc-magnetometry. It is shown that TmF3 is a Van Vleck paramagnet. Zero field splitting between two lowest ground state energy levels (ground 3H6 multiplet) of Tm3+ ion in TmF3 crystal lattice is found to be ∼6.5 cm-1. The 19F nuclear spin-lattice relaxation in TmF3 at liquid helium temperatures is driven by the fluctuating magnetic fields created by Tm3+ ions occupying the lowest excited singlet.