Unified research on the optical and EPR spectral data for the Cr³⁺ ion in the low-temperature trigonal phase of a LaAlO₃ crystal

¹ School of Physics & Electronic Engineering, Mianyang Normal University, 621000 Mianyang, P.R. China
² Research Center of Computational Physics, Mianyang Normal University 621000 Mianyang, P.R. China
³ Department of Material Science, Sichuan University, 610064 Chengdu, P.R. China

^a e-mail: zhengwc1@163.com

Received: 7 April 2015
Revised: 6 June 2015
Accepted: 11 August 2015
Published online: 27 August 2015

Abstract

The crystal field energy levels (or optical band positions) and EPR parameters (g factor g//, g⊥ and zero-field splitting D) for the Cr³⁺ ion in the trigonal phase of a LaAlO₃ crystal are calculated together through the complete diagonalization (of energy matrix) method. The method is founded on the two-spin-orbit-parameter model in which the contributions from both the spin-orbit parameter of the central dⁿ ion and that of the ligand ion (the latter is ignored in the conventional crystal field theory) are considered. From the calculations, the observed seven optical band positions and three EPR parameters (g//, g⊥, D) for LaAlO₃:Cr³⁺ at T ≈ 4.2 K are reasonably and unifiedly explained with only four adjustable parameters, and the impurity-induced local angular distortion of the Cr³⁺ center in LaAlO₃ is estimated.