Terahertz spin dynamics driven by an optical spin-orbit torque

Abstract

Spin torques are at the heart of spin manipulations in spintronic devices. Here, we examine the existence of an optical spin-orbit torque, a relativistic spin torque originating from the spin-orbit coupling of an oscillating applied field with the spins. We compare the effect of the nonrelativistic Zeeman torque with the relativistic optical spin-orbit torque for ferromagnetic systems excited by a circularly polarised laser pulse. The latter torque depends on the helicity of the light and scales with the intensity, while being inversely proportional to the frequency. Our results show that the optical spin-orbit torque can provide a torque on the spins, which is quantitatively equivalent to the Zeeman torque. Moreover, temperature dependent calculations show that the effect of optical spin-orbit torque decreases with increasing temperature. However, the effect does not vanish in a ferromagnetic system, even above its Curie temperature.

arXiv comment8 pages, 6 figures

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• Terahertz spin dynamics driven by a field-derivative torque
• Broadband Circular Polarization Time-Domain Terahertz Spectroscopy

Cited by in corpus (4)

• Influence of inter-sublattice coupling on the terahertz nutation spin dynamics in antiferromagnets
• Role of material-dependent properties in THz field-derivative-torque-induced nonlinear magnetization dynamics
• Field-derivative torque induced magnetization reversal in ferrimagnetic Gd${}_{3/2}$Yb${}_{1/2}$BiFe${}_5$O${}_{12}$
• Optically induced magnetic inertia and magnons from non-Markovian extension of the Landau-Lifshitz-Gilbert equation