Current-driven skyrmion dynamics in disordered films

Reference: J.-V. Kim and M.-W. Yoo, Appl. Phys. Lett. 110, 132404 (2017).

We studied how current-driven skyrmion motion in ultrathin films is affected by disorder. We modelled the disorder by assuming a grain structure, where the local perpendicular anisotropy fluctuates from grain to grain. We find that the velocity versus current curves are reminiscent of behavior in driven elastic interfaces in disordered media, such as domain wall creep. Moreover, we identify an extrinsic contribution to the skyrmion Hall effect due to disorder scattering, which is drive dependent. This work has just appeared in Applied Physics Letters.

Siphoning spins

511418a-f1

A News & Views piece I wrote for Nature has just appeared.

Topological insulators are well-known for their exotic electron-transport properties. A Letter out in this week describes how the spin-polarized currents at the surface of a topological insulator can be used to generate large spin-transfer torques in a transition metal ferromagnet. These torques are at least an order of magnitude larger than those generated by the spin Hall effect with heavy-metal substrates.