Coexistence of non-trivial van der Waals magnetic orders enable field-free spin-orbit torque switching at room temperature

Abstract

The discovery of van der Waals (vdW) magnetic materials exhibiting non-trivial and tunable magnetic interactions can give rise to exotic magnetic states, which are not readily attainable with conventional materials. Such vdW magnets can provide a unique platform for studying new magnetic phenomena and realizing magnetization dynamics for energy-efficient and non-volatile spintronic memory and computing technologies. Here, we discover the coexistence of ferromagnetic and antiferromagnetic orders in vdW magnet (Co0.5Fe0.5)5-xGeTe2 (CFGT) CFGT above room temperature, inducing an intrinsic exchange bias and canted perpendicular magnetism. Such non-trivial intrinsic magnetic order enables us to realize energy-efficient, magnetic field-free, and deterministic spin-orbit torque (SOT) switching of CFGT in heterostructure with Pt. The devices show a very large spin Hall conductivity, a low critical current density, and yield a large SOT effective field. These experiments, together with density functional theory and Monte Carlo simulations establish coexisting non-trivial magnetic orders in CFGT that enable field-free SOT magnetization dynamics in spintronic devices.