Spectroscopic properties of LiErF₄

Abstract

Polarized absorption and magnetic circular dichroism (MCD) spectra of an LiErF₄ single crystal have been recorded at different temperatures between liquid-helium temperature and room temperature. Assignments are made assuming D_2d symmetry for the coordination polyhedron around the trivalent erbium ion. The energy level scheme is parametrized in terms of 20 free-ion and 5 B_q^k crystal-field parameters. The optimized set of crystal-field parameters is: B₀² = 303.3 cm⁻¹, B₀⁴ = −773.3 cm⁻¹, B₄⁴ = −935.0 cm⁻¹, B₀⁶ = −59.9 cm⁻¹ and B₄⁶ = −665.9 cm⁻¹. Intensities of transitions between crystal-field levels are parametrized by a set of A_tp^λ intensity parameters. The reliability of the parameter sets is tested by graphical simulation of the experimental MCD spectra.