Twisted light affects ultrafast demagnetization

TL;DR

This paper demonstrates experimentally that the orbital angular momentum of ultrashort laser pulses influences the ultrafast demagnetization process in nickel thin films, revealing a new role for light's angular momentum in spin dynamics.

Contribution

It provides the first experimental evidence that the orbital angular momentum of light can affect ultrafast magnetic demagnetization, expanding understanding of light-matter interactions.

Findings

OAM influences demagnetization within hundreds of femtoseconds

Handedness of OAM affects the demagnetization behavior

Light's orbital angular momentum can modulate magnetic dynamics

Abstract

Irradiation with an ultrashort laser pulse can completely destroy the magnetic order of ferromagnetic thin films on the femtosecond timescale. This phenomenon holds great potential for ultrafast spintronics and information processing and is an active field of research. It is still an open question if the angular momentum of light can support this effect. While it has been shown that the spin of light only has a negligible influence, we experimentally demonstrate the influence of ultrashort laser pulses with orbital angular momentum (OAM) on the magnetization dynamics of a thin nickel film. Our results reveal that the photonic OAM affects the demagnetization behavior within the first hundreds of femtoseconds depending on the handedness of the OAM with respect to the direction of the sample magnetization.