Theoretical studies of 63Cu Knight shifts of the normal state of YBa2Cu3O7

TL;DR

This paper provides a theoretical analysis of 63Cu Knight shifts in the normal state of YBa2Cu3O7, showing good agreement with experimental data and highlighting the role of orbital interactions in anisotropy.

Contribution

The study applies high-order perturbation formulas to accurately model Knight shifts and g factors, improving upon previous models with fewer adjustable parameters.

Findings

Good agreement between theoretical and observed Knight shifts.

Anisotropy mainly due to orbital interaction-induced g factor anisotropy.

Quantitative correlation with local Cu2+ structure.

Abstract

The 63Cu Knight shifts and g factors for the normal state of YBa2Cu3O7 in tetragonal phase are theoretically studied in a uniform way from the high (fourth-) order perturbation formulas of these parameters for a 3d9 ion under tetragonally elongated octahedra. The calculations are quantitatively correlated with the local structure of the Cu2+(2) site in YBa2Cu3O7. The theoretical results show good agreement with the observed values, and the improvements are achieved by adopting fewer adjustable parameters as compared to the previous works. It is found that the significant anisotropy of the Knight shifts is mainly attributed to the anisotropy of the g factors due to the orbital interactions.