Optical and magnetic properties of Er3+ in LiYF4

High-resolution, polarized fluorescence spectroscopy has been used to study magnetically split energy levels of triply ionized erbium in the scheelite host lithium yttrium fluoride. Primary attention focused upon characterizing the Stark components of JLS manifolds involved in the material's several lasing transitions. Measurements at 2K yield energies and signed g factors which differ considerably from previously published zero-field studies and corresponding theoretical predictions of magnetic splittings. Polarization data allow definitive assignment of S₄ irreducible representations similar to those reported for erbium levels in the isomorphic host CaWO₄. Summation of g∥'s for the three Γ_7,8 levels of the ${}^4\text{I}{}_{\mathrm{<mtext>13</mtext><mtext>2</mtext>}}$ multiplet yields a value of 3.16 ± 0.23, whereas the recently developed partial g-sum rule predicts 3.32.