Photons carry spin angular momentum in circularly-polarized and orbital angular momentum in vortex electromagnetic waves.
The inverse Faraday effect has been observed in which magnetization appears during the dwell time when circularly-polarized light passes through a dielectric medium.
For pure Co "field-like torque" sine wave and for Co35Pt65 alloy "damping-like torque" cosine wave were observed. These torques exert on a magnetic moment due to a spin current, a field-like torque acts like an external magnetic field, aligning the magnetization in a specific direction, while a damping-like torque opposes the magnetization's change in direction, similar to friction.
The Landau-Lifshitz equation was used here which describes how the magnetization changes over time due to the influence of applied torques.
γ, µ0, and Heff are the gyromagnetic ratio, vacuum permeability, and effective magnetic field, respectively.
A reduction of the Kerr effect (when polarized light reflects off a magnetized material and undergoes a change in polarization direction and ellipticity) was observed with an increase in the Pt concentration.
Source:
https://arxiv.org/abs/2405.07405
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