Rectification in Spin-Orbit Materials Using Low-Energy-Barrier Magnets

Abstract

The coupling of spin-orbit materials to high-energy-barrier (approximately 40-60 kBT) nanomagnets has recently attracted growing interest due to exciting new physics and various spintronic applications. We predict that a coupling between the spin-momentum locking (SML) observed in spin-orbit materials and low-energy-barrier magnets (LBMs) should exhibit a unique multiterminal rectification for arbitrarily small-amplitude channel currents. The basic idea is to measure the charge-current-induced spin accumulation in the SML channel in the form of a magnetization-dependent voltage using an LBM, either with an in-plane or perpendicular anisotropy (IMA or PMA, respectively). The LBM feels an instantaneous spin-orbit torque due to the accumulated spins in the channel, which causes the average magnetization to follow the current, leading to the nonlinear rectification. We discuss the frequency band of this multiterminal rectification, which can be understood in terms of the angular-momentum conservation in the LBM. For a fixed spin-current from the SML channel, the frequency band is same for LBMs with IMA and PMA, as long as they have the same total magnetic moment in a given volume. The proposed all-metallic structure could find application as a highly sensitive passive radio-frequency (rf) detector and as an energy harvester from weak ambient sources, where standard technologies may not operate.