Anisotropy of the orbital methods and the magnetic dipole term $T_z$ in ${\rm CrO_2}$: An {\it ab-initio} studt

TL;DR

This study uses ab-initio density functional theory to analyze the anisotropy of orbital moments and the magnetic dipole term in bulk CrO2, comparing different computational methods and electronic correlation treatments.

Contribution

It provides a systematic ab-initio analysis of orbital and magnetic dipole anisotropies in CrO2 using multiple computational techniques and correlation models.

Findings

Large anisotropies of <l_z> and <T_z> compared to Fe, Ni, Co

Calculated anisotropies are smaller than those suggested by X-ray dichroism analysis

Different computational methods yield consistent anisotropy trends

Abstract

A systematic study is performed by the {\it ab-initio} density functional theory of the anisotropy of the orbital moments $<l_z>$ and the magnetic dipole term $<T_z>$ in bulk ${\rm CrO_2}$. Two different band-structure techniques are used (FLAPW and LMTO-ASA), and the electronic correlations are treated by the local-spin-density approximation (LSDA), the LSDA+ orbital polarization method, and the LSDA+$U$ method. The calculated anisotropies of $<l_z>$ and $<T_z>$ are very large compared to Fe, Ni and Co but still a factor of 5 and 2 smaller than the anisotropies obtained from a recently suggested analysis of the X-ray magnetic circular dichroism spectra for a thick layer of ${\rm CrO_2}$.