# Terahertz antiferromagnetic dynamics induced by ultrafast spin currents

## TL;DR

Researchers show that magnetic information can be transferred to antiferromagnetic insulators at ultrafast speeds using terahertz spin currents.

## Contribution

Demonstration of terahertz spin current-induced antiferromagnetic dynamics in insulators.

## Key findings

- Coherent terahertz excitations are generated in antiferromagnetic insulators.
- Demagnetization behavior in the ferromagnet is modulated by the spin current.
- Magnetic information can be transferred to antiferromagnets at picosecond timescales.

## Abstract

Insulating antiferromagnets are anticipated as the main protagonists of ultrafast spintronics, with their intrinsic terahertz dynamics and their ability to transport spin information over long distances. However, ultrafast transfer of spin angular momentum to an antiferromagnetic insulator remains to be demonstrated. Here, studying the picosecond and subpicosecond dynamics of ferromagnetic metal/antiferromagnetic insulator bilayers, we evidence the generation of coherent terahertz excitations in the antiferromagnet combined with a modulation of the demagnetization behavior in the ferromagnet. We thus demonstrate that magnetic information can indeed be propagated into antiferromagnetic spin waves at picosecond timescales, thereby opening an avenue toward ultrafast manipulation of magnetic information.

Terahertz spin information is transferred to antiferromagnetic insulators.