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.
We show how inhomogeneous spin polarizers in the form of vortices can result in self-sustained gyration of skyrmions in magnetic nanopillars. We suggest that such dynamics could be useful for skyrmion-based spin-torque nano-oscillators. This work has just appeared in the New Journal of Physics.
By using analytical theory and micromagnetics simulations, we helped to explain experimental observations of an asymmetry in current-induced magnetization switching in ultrathin CoFeB/MgO films. This work has just appeared in Physical Review B.
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.
Our paper on moving vortices around using multiple nanocontacts has appeared in Nature Nanotechnology! There is an accompanying News & Views piece by Prof. Teruo Ono of Kyoto University.