Terahertz spin dynamics driven by an optical spin-orbit torque

Autor: Ritwik Mondal, Andreas Donges, Ulrich Nowak
Jazyk: angličtina
Rok vydání: 2021
Předmět:
Zdroj: Physical Review Research, Vol 3, Iss 2, p 023116 (2021)
Druh dokumentu: article
ISSN: 2643-1564
DOI: 10.1103/PhysRevResearch.3.023116
Popis: 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 polarized 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.
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