Spin-transfer torque in magnetic tunnel junctions: Scattering theory

Abstract

We study the bias-dependent spin-transfer torque in magnetic tunnel junctions in the Stoner model by scattering theory. We show that the in-plane (Slonczewski type) torque vanishes and subsequently reverses its direction when the bias voltage becomes larger or the barrier wider than material and device-dependent critical values. We are able to reproduce the magnitude and the bias dependence of measured in-plane and out-of-plane torques using realistic parameters. The condition for the vanishing torque is summarized by a phase diagram depending on the applied bias and barrier width, which is explained in terms of an interface spin polarization and the electron focusing by the barrier. Quantum size effects in the spin-transfer torque are predicted as a function of the thickness of a normal metal layer inserted between the ferromagnet and tunnel barrier.

10 pages, 10 figures. to be published on Physical Review B

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• Bias dependence of magnetic exchange interactions: application to interlayer exchange coupling in spin valves
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• Analytical description of ballistic spin currents and torques in magnetic tunnel junctions
• Spin-Torque Diode Measurements of MgO-Based Magnetic Tunnel Junctions with Asymmetric Electrodes
• Spin-Transfer Torque and Magnetoresistance in Superconducting Spin-Valves
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• First-principles quantum transport modeling of spin-transfer and spin-orbit torques in magnetic multilayers
• How to construct the proper gauge-invariant density matrix in steady-state nonequilibrium: Applications to spin-transfer and spin-orbit torques
• Influence of the magnetic material on tunneling magnetoresistance and spin-transfer torque in tunnel junctions: Ab initio studies
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• Signatures of asymmetric and inelastic tunneling on the spin torque bias dependence
• Spin switching via quantum dot spin valves
• Theoretical Study of Spin-Torque Oscillator with Perpendicularly Magnetized Free Layer
• Thermal spin-transfer torque in magnetic tunnel junctions
• Spin transparency for an interface of an ultrathin magnet within the spin dephasing length
• Spin Torque in Anisotropic Tunneling Junctions
• Spin transport and tunable Gilbert damping in a single-molecule magnet junction
• Stable oscillation in spin torque oscillator excited by a small in-plane magnetic field
• Voltage-input spintronic oscillator based on competing effect for extended oscillation regions
• Effects of screened Coulomb interaction on spin transfer torque
• Photon-assisted electronic and spin transport in a junction containing precessing molecular spin
• Resonance spin transfer torque in ferromagnetic/normal/ferromagnetic spin-valve structure of topological insulators
• Spin-torque generation by dc or ac voltages in magnetic layered structures
• Spin torque from tunneling through impurities in a magnetic tunnel junction
• Enhancement of the spin transfer torque efficiency in magnetic STM junctions
• Twist in the bias-dependence of spin-torques in magnetic tunnel junctions
• Effect of interfacial spin mixing conductance on gyromagnetic ratio of Gd substituted Y${}_3$Fe${}_5$O${}_{12}$
• Enhancement of spin mixing conductance by $s$-$d$ orbital hybridization in heavy metals
• Microscopic theory of the Coulomb based exchange coupling in magnetic tunnel junctions
• Giant spin transfer torque in atomically thin magnetic bilayers
• Adiabatic quantum pumping, magnification effects and quantum size effects of spin-torque in magnetic tunnel junctions
• Voltage-driven v.s. Current-driven Spin Torque in Anisotropic Tunneling Junctions
• Gate-dependent spin-torque in a nanoconductor-based spin-valve
• Spin transfer torque enhancement in dual spin valve in the ballistic regime
• Theory of high-resolution tunneling spin transport on a magnetic skyrmion
• Influence of image forces on the interlayer exchange interaction in magnetic tunnel junctions with ferroelectric barrier