Theory of atomistic simulation of spin-transfer torque in nanomagnets

Abstract

In spin-transfer torque (STT) for technological applications, the miniaturization of the magnet may reach the stage of requiring a fully quantum-mechanical treatment. We present an STT theory which uses the quantum macrospin ground and excited (magnon) states of the nanomagnet. This allows for energy and angular momentum exchanges between the current electron and the nano-magnet. We develop a method of magnetization dynamics simulation which captures the heating effect on the magnet by the spin-polarized current and the temperature-dependence in STT. We also discuss the magnetostatics effect on magnon scattering for ferromagnetic relaxation in a thin film. Our work demonstrates a realistic step towards simulation of quantum spin-transfer torque physics in nano-scale magnets.

12 pages, 8 figures

References in corpus (2)

• Coherent Magnetization Precession in GaMnAs induced by Ultrafast Optical Excitation
• Quantum Dynamics of a Nanomagnet driven by Spin-Polarized Current

Cited by in corpus (5)

• Quantum spin-transfer torque induced nonclassical magnetization dynamics and electron-magnetization entanglement
• Spintronics meets density matrix renormalization group: Quantum spin torque driven nonclassical magnetization reversal and dynamical buildup of long-range entanglement
• Quantum many-body states and Green functions of nonequilibrium electron-magnon systems: Localized spin operators vs. their mapping to Holstein-Primakoff bosons
• Magnetization Dynamics driven by Non-equilibrium Spin-Orbit Coupled Electron Gas
• Unquenched orbital angular momentum as the origin of spin inertia