Electron-Paramagnetic-Resonance Spectra of Nd3+, Dy3+, Er3+, and Yb3+ in Lithium Yttrium Fluoride

Abstract

The electron-paramagnetic-resonance spectra have been obtained for trivalent neodymium, dysprosium, erbium, and ytterbium in single-crystal samples of the scheelite lithium yttrium fluoride. The measurements were made at $X$-band frequencies and at 4.2 °K. The ions were found to have axial spectra which, together with chemical arguments, indicate that they occupy ${\mathrm{Y}}^{3+}$ sites with $S_4$ point symmetry. $g$ factors and hyperfine parameters were obtained by the complete diagonalization of the spin Hamiltonian and least-squares fitting to the observed spectra. The ground-state irreducible representations for ${\mathrm{Yb}}^{3+}$ and ${\mathrm{Nd}}^{3+}$ were determined to be ${\Gamma }_{5,6}$ and ${\Gamma }_{7,8}$, respectively. Superhyperfine structure was observed in the ${\mathrm{Yb}}^{3+}$ $c$-axis spectrum.