Zero-field splitting of a⁶S-state ion in tetragonal symmetry

Abstract

The perturbation proceduressuggested in the spin-orbit (so) couplingmechanism contibuting to the %-state splitting are examined in detail and round to be all correct for tetragonal symmetry, on the basis of a diagonalization calculation. The BlumMrbach procedure is most appropriate. The sixth-order perturbation must be taken into account in strong fields for the procedure proposed by Watanabe and developed by Yu and Zhao, and the expression is given here Among the various mechanisms which contribute to the zero-field splitting of %-state ions, the spin-orbit (SO) coupling mechanism has been found to be most important for many substances and thus has become the subject of many recent papers [I-51. There areat least three altemative approaches to the perturbation procedure [ 11. Among them the well known and extensively used Blume-Orbach procedures [6, 71 (called so-I hereafter) was recently indicated as not appropriate for rhombic symmetry [3]. The procedure proposed by Watanabe [8] and developed by Yu and Zhao [2] (denoted