All-optical non-linear chiral ultrafast magnetization dynamics driven by circularly polarized magnetic fields

TL;DR

This paper demonstrates that circularly polarized magnetic fields can induce a purely precessional, non-linear, chiral ultrafast magnetization response, opening new avenues for all-optical, non-thermal magnetic switching at unprecedented timescales.

Contribution

It reveals the fundamental non-linear chiral magnetization dynamics driven by circularly polarized magnetic fields, distinct from electric field effects in ultrafast laser interactions.

Findings

Demonstrates non-linear, chiral magnetization response to circularly polarized magnetic fields.

Shows potential for ultrafast, all-optical magnetic switching at attosecond and THz regimes.

Unveils a new mechanism for laser-induced ultrafast magnetization control.

Abstract

Ultrafast laser pulses provide unique tools to manipulate magnetization dynamics at femtosecond timescales, where the interaction of the electric field -- such as excitation of spin carriers to non-equilibrium states, generation of localized charge currents, demagnetization, or inverse Faraday effect -- dominates over the magnetic field. Recent proposals using structured laser beams have enlightened the possibility to generate intense femtosecond magnetic fields, spatially isolated from the electric field. Here we demonstrate the relevance of this novel scenario to femtomagnetism, unveiling the purely precessional, non-linear, chiral response of the magnetization when subjected to circularly polarized magnetic fields. This fundamental result not only opens an avenue in the study of laser-induced ultrafast magnetization dynamics, but also sustains technological implications as a route to promote all-optical non-thermal magnetization switching both at shorter timescales -- towards the attosecond regime -- and at THz frequencies.