Observation of anomalous spin-torque generated by a ferromagnet

Abstract

In this work we report observation of in-plane current induced out-of-plane magnetic field driven torque in spin valve structure. Since ferromagnet has high spin orbit coupling it is expected to be the source of spin-orbit-torque as it possesses anomalous-Hall-effect (AHE: equivalent to spin Hall effect in heavy metal). So we have carried out spin-torque ferromagnetic resonance (ST-FMR) experiment in a spin valve (consists of a fixed magnet and a free magnet which are separated by Cu spacer), passing in-plane radio frequency current and measuring DC voltage. Our experimental results eventually indicate that spin torque exerted on the free magnet is not caused due to the spin current injection by the fixed magnet owing to its AHE, but it is originated from in-plane current driven out-of plane effective magnetic field. This is new class of spin torque which is completely different from Slonczewski-spin transfer torque and Rashba like field like torque. The effective out-of plane magnetic field depends on the direction of current (in-plane) and magnetization (in-plane) of the pinned layer. One possible mechanism behind this unconventional torque could be intefacial spin-scattering which is also origin of current in-plane GMR effect. Most importantly this effective out-of plane torque can be useful to switch out-of plane magnetic bits in spintronic memory application.

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• Current-induced spin-orbit torques in ferromagnetic and antiferromagnetic systems
• Tilted spin current generated by the collinear antiferromagnet RuO2
• Interface-generated spin currents
• Intrinsic spin currents in ferromagnets
• An Intrinsic Spin Orbit Torque Nano-Oscillator
• Magnetic asymmetry induced anomalous spin-orbit torque in IrMn
• Origin of the Magnetic Spin Hall Effect: Spin Current Vorticity in the Fermi Sea
• Interfacial spin-orbit torques
• Large Spin Anomalous Hall Effect in L1${}_0$-FePt: Symmetry and Magnetization Switching
• Magnetization switching induced by spin-orbit torque from Co2MnGa magnetic Weyl semimetal thin films
• Spin-orbit torque for field-free switching in C_{3v} crystals
• Generation of n-qubit W states using Spin Torque
• Control of magnetization dynamics by spin Nernst torque
• Large anomalous Nernst effect across the magneto-structural transition in bulk Ni-Co-Mn-Sn full Heusler alloy
• Exchange-driven spin Hall effect in anisotropic ferromagnets
• Enhancement of Spin-Charge Conversion Efficiency for Co${}_3$Sn${}_2$S${}_2$ across Transition from Paramagnetic to Ferromagnetic Phase
• Transmission based tomography for spin qubits
• Magnetoresistance originated from charge-spin conversion in ferromagnet
• Theory of magnetic spin and orbital Hall and Nernst effects in bulk ferromagnets