Single crystal EPR spectrum of Cr³⁺ in lanthanum lutecium gallium garnet

Abstract

The Cr³⁺ EPR spectra of YAG type crystals normally consist of four peaks whose positions are dependent on the axial zero-field splitting D with axis along a 〈111〉 direction and angle ϑ between that direction and the applied field H ₀. In LLGG only three principal peaks are observed with zero-field axis nearly along x, y or z. This anomaly is attributed to the relatively small size of Cr³⁺ compared to Lu³⁺ which it displaces in an octahedral site. D varies slightly for the different zero-field axes: 0.480 cm⁻¹ along x, 0.429 cm⁻¹ along y and 0.470 cm⁻¹ along z. The spectroscopic splitting factor g=1.978±0.001 is essentially isotropic and independent of axes within the experimental error.