Correlation Effects on Magnetic Anisotropy in Fe and Ni

TL;DR

This paper investigates how strong electronic correlations, spin-orbit coupling, and non-collinearity influence magnetic anisotropy energy in Fe and Ni, using the LDA+U method and exploring parameter space to match experimental data.

Contribution

It demonstrates the application of the LDA+U method to accurately predict magnetic anisotropy energy and magnetization directions in Fe and Ni, linking strong correlations with magnetic properties.

Findings

Accurate prediction of MAE magnitude and direction at specific U and J values.

Establishment of equivalence between LDA+U and dynamical mean-field theory in the static limit.

Emphasis on the impact of strong correlations on electronic spectra and magnetic anisotropy.

Abstract

We calculate magnetic anisotropy energy of Fe and Ni by taking into account the effects of strong electronic correlations, spin-orbit coupling, and non-collinearity of intra-atomic magnetization. The LDA+U method is used and its equivalence to dynamical mean-field theory in the static limit is derived. The effects of strong correlations are studied along several paths in $(U,J)$ parameter space. Both experimental magnitude of MAE and direction of magnetization are predicted correctly near $U=1.9 eV$, $J=1.2 eV$ for Ni and $U=1.2 eV$, $J=0.8 eV$ for Fe. The modified one-electron spectra by strong correlations are emphasized in conjunction with magnetic anisotropy.