  Ultra-thin film of FeRh on insulator MgO substrate has been investigated
usingab-initio electronic structure calculations. From this calculation, we
have found the interesting effect of epitaxial strain on the magnetocrystalline
anisotropy (MCA). Analysis of the energy and k-resolved distribution of the
orbital character of the band structure reveals that MCA largely arises from
the spin-orbit coupling (SOC) between dx2-y2 andd xz,yz orbitals of Fe atoms at
the FeRh/MgO interface. We demonstrate that the strain has significant effects
on the MCA: It not only affects the value of the MCA but also induces a
switching of the magnetic easy axis from perpendicular to in-plane direction.
The mechanism is the strain-induced shifts of the SOC d-states. Our work
demonstrates that strain engineering can open a viable pathway towards
tailoring magnetic properties for antiferromagetic spintronic applications.
