Theoretical studies on the local structure and spin Hamiltonian parameters for Cu²⁺ ions in LiTaO₃ crystal

Abstract

The local structure and spin Hamiltonian parameters (SHPs) g factors (gx, gy, gz) and the hyperfine structure constants (Ax, Ay, Az) for Cu2+ doped in the LiTaO3 crystal are theoretically investigated by the perturbation formulas for a 3d9 ion under rhombically elongated octahedral based on the cluster approach. The impurity Cu2+ was assumed to occupy the host trigonally‐distorted octahedral Li+ site and experience the Jahn–Teller (JT) distortion from the host trigonal octahedral [TaO6]10− to the impurity rhombically elongated octahedral [CuO6]10−. Based on the calculations, the impurity‐ligand bond lengths parallel and perpendicular to the C2‐axis are found to be R||(≈ 2.305 Å) and R⊥ (≈ 2.112 Å) for the studied [CuO6]10− cluster, with the planar bond angle θ (≈ 78.2°). Meanwhile, the ground‐state wave function for Cu2+ center in LiTaO3 was also obtained. The calculated SHPs based on the above local lattice distortions agree well with the experimental data, and the results are discussed.