Spin-orbit coupling induced anisotropy effects in bimetallic antiferromagnets: A route towards antiferromagnetic spintronics

Magnetic anisotropy phenomena in bimetallic antiferromagnets ${\text{Mn}}_2\text{Au}$ and MnIr are studied by first-principles density-functional theory calculations. We find strong and lattice-parameter-dependent magnetic anisotropies of the ground-state energy, chemical potential, and density of states, and attribute these anisotropies to combined effects of large moment on the $\text{Mn}3d$ shell and large spin-orbit coupling on the $5d$ shell of the noble metal. Large magnitudes of the proposed effects can open a route towards spintronics in compensated antiferromagnets without involving ferromagnetic elements.

Figure 1

(Color online) Total DOS (per f.u.), spin-resolved Au-atom and Mn-atom projected DOSs, and a schematic view of the crystal and AFM structure of ${\text{Mn}}_2\text{Au}$. (Mn-I denotes one of two Mn sublattices with opposite spin polarizations.)

Figure 2

(Color online) (a) DOS anisotropies for the hard ([001]) and easy ([110]) axes of ${\text{Mn}}_2\text{Au}$, and the hard ([001]) and easy ([100]) axes of MnIr. (b) In-plane DOS anisotropies for staggered moment aligned along the easy axis ([010]) of the strained ${\text{Mn}}_2\text{Au}$ crystal and along the easy axis ([110]) of the unstrained ${\text{Mn}}_2\text{Au}$. The energy is measured from the Fermi level.