We theoretically study the current-induced spin torque in antiferromagnetic tunnel junctions, composed of two semi-infinite antiferromagnetic layers separated by a tunnel barrier, in both clean and disordered regimes. We find that the torque enabling the electrical manipulation of the N\'eel antiferromagnetic order parameter is out of plane $\sim { \bf n}\times{ \bf p}$, while the torque competing with the antiferromagnetic exchange is in-plane $\sim { \bf n}\times({ \bf p}\times{ \bf n})$. Here, ${ \bf { p}}$ and ${ \bf { n}}$ are the N\'eel order parameter direction of the reference and free layers, respectively. Their bias dependence shows similar behavior as in ferromagnetic tunnel junctions, the in-plane torque being mostly linear in bias while the out-of-plane torque is quadratic. Most importantly, we find that the spin transfer torque in antiferromagnetic tunnel junctions is much more robust against disorder than in antiferromagnetic metallic spin-valves due to the tunneling nature of spin transport.
Categories: cond-mat.mes-hall