Masashi MIURA

We present spin–orbit torque (SOT) field free magnetization switching and the detection of magnetization at room temperature using Pt and Sn alloys. Observations of the planar Hall effect and weak antilocalization provide evidence of topological features present in the PtSn4. The figures of merit of the spin-torque efficiency and spin-to-charge conversion (SCC) were estimated to be as large as 0.31 ± 0.02 and 0.47 ± 0.08, respectively, in Pt1Sn1. High SOT efficiency, large SCC signal, low magnetization switching current density, and industry compatibility for large-scale production have led to the application of PtxSn1−x alloys in magnetic memory and logic devices.

Abstract Iron-based 1111-type superconductors display high critical temperatures and relatively high critical current densities J_c. The typical approach to increasing J_c is to introduce defects to control dissipative vortex motion. However, when optimized, this approach is theoretically predicted to be limited to achieving a maximum J_c of only ∼30% of the depairing current density J_d, which depends on the coherence length and the penetration depth. Here we dramatically boost J_c in SmFeAsO_1–xH_x films using a thermodynamic approach aimed at increasing J_d and incorporating vortex pinning centres. Specifically, we reduce the penetration depth, coherence length and critical field anisotropy by increasing the carrier density through high electron doping using H substitution. Remarkably, the quadrupled J_d reaches 415 MA cm^–2, a value comparable to cuprates. Finally, by introducing defects using proton irradiation, we obtain high J_c values in fields up to 25 T. We apply this method to other iron-based superconductors and achieve a similar enhancement of current densities.