Effect of exchange-correlation spin-torque on spin dynamics

Abstract

A recently proposed exchange-correlation functional (Dewhurst et al. 10.1021/acs.jctc.7b01049) with in density functional theory, which ensures that the exchange-correlation magnetic field is source-free, is shown to give non-zero internal spin-torque. This spin-torque is identically zero for all conventional local and semi-local functionals. Extension of this source-free functional to the time domain is used to study the effect of the internal spin-torque on the laser induced spin-dynamics in bulk Co, Ni and interfaces of these metals with Pt. It is shown that the internal spin-torque contribute significantly to spin-dynamics only when the magneto crystalline anisotropy energy is small, as in the case of cubic bulk materials. For surfaces or interfaces, where the anisotropy energy is large, these torques are too small to cause any significant precession of spins in early times ($<$ 100fs). Further more it is shown that the spin-dynamics caused by the internal spin-torque is slow compared to the inter-site spin transfer and spin-orbit mediated spin-flips.

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References in corpus (4)

• Nanoscale confinement of ultrafast spin transfer torque exciting non-uniform spin dynamics by femtosecond spin current pulses
• Role of Spin Flips versus Spin Transport in Non Thermal Electrons Excited by Ultrashort Optical Pulses in Transition Metals
• Absorption and generation of femtosecond laser-pulse excited spin currents in non-collinear magnetic bilayers
• Ab initio dynamical exchange interactions in frustrated anti-ferromagnets

Cited by in corpus (7)

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• Physical spin torques from exactly constrained exchange-correlation torques
• Ultrafast Spin Injection in Graphene via Dynamical Carrier Filtering at Transition Metal Dichalcogenide Interfaces