Zero-Threshold Rectification Using Low-Barrier Magnets

Stable magnets with energy barriers (~40-60 k_BT) have been the center of focus for spintronics. Recently, low energy barrier magnets have attracted growing interest in the community for novel applications e.g. random number generation, stochastic oscillators, probabilistic computers, etc. Using experimentally benchmarked models [1,2], we show that the charge current induced spin voltage measurements, well-established for diverse materials with spin-orbit coupling, could be used for zero-threshold rectification when the stable magnet is replaced with a low barrier magnet either with an in-plane or perpendicular anisotropy. These experiments can be used to characterize such stochastic magnets and extract parameters that determine (i) spin-orbit torque induced magnetization pinning and (ii) the frequency band of rectification. We analytically determine this frequency band from angular momentum conservation principles. The proposed structure could find application as highly sensitive passive rf detectors and as energy harvesters from weak ambient sources where standard technologies may not operate.
[1] Phys. Rev. Applied, Oct. 2018 (arXiv:1707.04051v3). [2] Phys. Rev. X, 7, 03101, 2017.