Influence of strain and chemical substitution on the magnetic anisotropy of antiferromagnetic Cr₂O₃: An ab-initio study

Authors

Sai Mu, University of Nebraska-Lincoln
Kirill D. Belashchenko, University of Nebraska-LincolnFollow

Date of this Version

3-12-2019

Citation

SAI MU AND K. D. BELASHCHENKO PHYSICAL REVIEW MATERIALS 3, 034405 (2019). DOI: 10.1103/PhysRevMaterials.3.034405

Comments

Used by permission.

Abstract

The influence of the mechanical strain and chemical substitution on the magnetic anisotropy energy (MAE) of Cr₂O₃ is studied using first-principles calculations. Dzyaloshinskii-Moriya interaction contributes substantially to MAE by inducing spin canting when the antiferromagnetic order parameter is not aligned with the hexagonal axis. Nearly cubic crystal field results in a very small MAE in pure Cr₂O₃ at zero strain, which is incorrectly predicted to be negative (in-plane) on account of spin canting. The MAE is strongly modified by epitaxial strain, which tunes the crystal-field splitting of the t_2g triplet. The contribution from magnetic dipolar interaction is very small at any strain. The effects of cation (Al, Ti, V, Co, Fe, Nb, Zr, Mo) and anion (B) substitutions on MAE are examined. Al increases MAE thanks to the local lattice deformation. In contrast, the electronic configuration of V and Nb strongly promotes easy-plane anisotropy, while other transition-metal dopants have only a moderate effect on MAE. Substitution of oxygen by boron, which has been reported to increase the Néel temperature, has a weak effect on MAE, whose sign depends on the charge state of B. The electric field applied along the (0001) axis has a weak second-order effect on the MAE.