2016

Spin swapping transport and torques in ultrathin magnetic bilayers

​Spin swapping transport and torques in ultrathin magnetic bilayers
H.B.M. Saidaoui and A. Manchon
Phys. Rev. Lett. 117, 036601 (2016)​
H.B.M. Saidaoui, A. Manchon
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2016
​Planar spin transport in disordered ultrathin magnetic bilayers comprising a ferromagnet and a normal metal (typically used for spin pumping, spin Seebeck and spin-orbit torque experiments) is investigated theoretically. Using a tight-binding model that puts the extrinsic spin Hall effect and spin swapping on equal footing, we show that the nature of spin-orbit coupled transport dramatically depends on the ratio between the layer thickness d and the mean free path λ. While the spin Hall effect dominates in the diffusive limit (d≫λ), spin swapping dominates in the Knudsen regime (d≲λ). A remarkable consequence is that spin swapping induces a substantial fieldlike torque in the Knudsen regime.