Ultrafast Spin Dynamics and Photoinduced Insulator-to-Metal Transition in $\alpha$-$RuCl_3$

TL;DR

This paper investigates how ultrafast laser pulses can induce rapid changes in the electronic and magnetic states of $ ext{RuCl}_3$, causing demagnetization and an insulator-to-metal transition within tens of femtoseconds, revealing insights into spin dynamics.

Contribution

The study employs time-dependent density functional theory to demonstrate laser-induced ultrafast demagnetization and insulator-metal transition in $ ext{RuCl}_3$, highlighting the role of laser parameters and electron correlations.

Findings

Ultrafast demagnetization occurs within tens of femtoseconds.

Laser pulses can induce an insulator-to-metal transition in $ ext{RuCl}_3$.

Spin response depends on laser wavelength and polarization.

Abstract

Laser-induced ultrafast demagnetization is a phenomenon of utmost interest and attracts significant attention because it enables potential applications in ultrafast optoelectronics and spintronics. As a spin-orbit coupling assisted magnetic insulator, $\alpha$-$RuCl_3$ provides an attractive platform to explore the physics of electronic correlations and related unconventional magnetism. Using time-dependent density functional theory, we explore the ultrafast laser-induced dynamics of the electronic and magnetic structures in $\alpha$-$RuCl_3$. Our study unveils that laser pulses can introduce ultrafast demagnetizations in $\alpha$-$RuCl_3$, accompanied by an out-of-equilibrium insulator-to-metal transition in a few tens of femtoseconds. The spin response significantly depends on the laser wavelength and polarization on account of the electron correlations, band renormalizations and charge redistributions. These findings provide physical insights into the coupling between the electronic and magnetic degrees of freedom in $\alpha$-$RuCl_3$ and shed light on suppressing the long-range magnetic orders and reaching a proximate spin liquid phase for two-dimensional magnets on an ultrafast timescale.