# Model of ultrafast demagnetization driven by spin-orbit coupling in a photoexcited antiferromagnetic insulator Cr2O3

## TL;DR

This paper models ultrafast demagnetization in Cr2O3 induced by laser pulses, revealing how electronic structure manipulation can control magnetic switching on femtosecond timescales.

## Contribution

It introduces a theoretical framework for understanding ultrafast demagnetization in antiferromagnetic insulators driven by spin-orbit coupling.

## Key findings

- Demagnetization occurs within hundreds of femtoseconds.
- Switching times can be reduced by tuning energy gaps.
- Relaxation times depend on orbital hybridization.

## Abstract

We theoretically study the dynamic time evolution following laser pulse pumping in an antiferromagnetic insulator Cr$_{2}$O$_{3}$. From the photoexcited high-spin quartet states to the long-lived low-spin doublet states, the ultrafast demagnetization processes are investigated by solving the dissipative Schr\"odinger equation. We find that the demagnetization times are of the order of hundreds of femtosecond, in good agreement with recent experiments. The switching times could be strongly reduced by properly tuning the energy gaps between the multiplet energy levels of Cr$^{3+}$. Furthermore, the relaxation times also depend on the hybridization of atomic orbitals in the first photoexcited state. Our results suggest that the selective manipulation of electronic structure by engineering stress-strain or chemical substitution allows effective control of the magnetic state switching in photoexcited insulating transition-metal oxides.