Cr -induced Perpendicular Magnetic Anisotropy and Field-Free Spin-Orbit-Torque Switching

Abstract

Perpendicular magnetization switching induced by spin-orbit torque (SOT) continues to attract great attention as a promising writing method for ultrafast, high-density, energy-efficient spintronic devices. Unfortunately, this otherwise very attractive switching scheme often comes with an unfavorable external magnetic field. Here the authors achieve polarity-controlled, $f\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}l\phantom{\rule{0}{0ex}}d\ensuremath{-}f\phantom{\rule{0}{0ex}}r\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}e$ SOT switching via oriented columnar microstructures in sputtered films. It is demonstrated that Cr---a $3d$, not $4d$, metal---can induce strong perpendicular magnetic anisotropy and generate large spin current to deliver SOT. These findings point to highly efficient, nonvolatile SOT spintronic devices.