Terahertz antiferromagnetic dynamics induced by ultrafast spin currents

TL;DR

This paper demonstrates that ultrafast spin currents can induce terahertz antiferromagnetic dynamics, enabling the transfer of magnetic information into antiferromagnetic insulators at picosecond timescales, advancing ultrafast spintronics.

Contribution

It provides experimental evidence of direct spin angular momentum transfer to antiferromagnetic insulators using ultrafast spin currents, a novel demonstration in the field.

Findings

Generation of coherent antiferromagnetic excitations

Modulation of ferromagnetic demagnetization behavior

Propagation of magnetic information into antiferromagnetic spin waves

Abstract

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