Investigations of the spin-Hamiltonian parameters for Yb³⁺ in the tetragonal phase of SrTiO₃ crystal

Abstract

The spin-Hamiltonian parameters (g factors, , , and hyperfine structure constants, , ) for Yb³⁺ at the 12-fold coordinated Sr²⁺ site of tetragonal SrTiO₃ crystal at T ≈ 2 and 50 K were calculated using the completed diagonalization (of the energy matrix) method (CDM). Differing from the conventional CDM, the Hamiltonian concerning the energy matrix in this CDM contains the Zeeman and hyperfine interaction terms and so the spin-Hamiltonian parameters can be calculated directly from CDM. The crystal parameters used in the energy matrix are calculated from the superposition model, in which the tetragonal distortions and hence the order parameters φ at both temperatures are applied. From the calculations, the spin-Hamiltonian parameters at both temperatures are explained reasonably and the signs of hyperfine structure constants for the ¹⁷¹Yb³⁺ and ¹⁷³Yb³⁺ isotopes in SrTiO₃ are suggested. The results are discussed.

Keywords:

• spin-Hamiltonian parameter
• ytterbium isotope
• hyperfine structure constant
• EPR

Acknowledgement

This project was supported by the National Natural Science Foundation of China (Grant No. 60890203).