Anisotropic magnetic susceptibility of single crystal UCl4

Abstract

The anisotropic magnetic susceptibilities χ_∥ and χ_⊥ of UCl₄ have been measured in single crystals between 1.6 and 350 K. Powder measurements of the average susceptibility were also performed but were found to be unreliable due to orientation effects. The single crystal results were interpreted in terms of the parametrized crystal field model with the following parameters: ζ=1819 cm⁻¹; F²=42 632 cm⁻¹, F⁴=38 680 cm⁻¹; F⁶=23 320 cm⁻¹; B²₀=−1008 cm⁻¹; B⁴₀=1730 cm⁻¹; B⁴₄=−2704 cm⁻¹; B⁶₀=−2705 cm⁻¹; B⁶₄=346 cm⁻¹; α=29 cm⁻¹; β=−638 cm⁻¹; and γ=1617 cm⁻¹. These parameters yield a Γ₄(³H₄) ground state and a paramagnetic first excited state Γ₅(³H₄) at 110 cm⁻¹ and are in good agreement with the optical spectrum.