Ultrafast N\'eel vector switching

TL;DR

This paper predicts and demonstrates femtosecond-scale Ne9el vector switching in chiral antiferromagnets, driven by ultrafast spin currents creating effective magnetic fields, enabling ultrafast magnetic control.

Contribution

It introduces a new physical mechanism for femtosecond switching in chiral antiferromagnets using ultrafast spin currents, with practical rules for maximizing these effects.

Findings

Ultrafast switching occurs at femtosecond timescales, five orders faster than previous methods.

Effective magnetic fields generated by ultrafast spin currents are key to rapid Ne9el vector rotation.

Switching between six non-collinear ground states of Mnb3Sn is achievable and reversible.

Abstract

We predict ultrafast switching in a chiral anti-ferromagnet that occurs at femtosecond times, nearly 5 orders of magnitude faster than the torque induced nanosecond switching previously observed. The physical mechanism, quite different from that which drives slow switching, involves the creation of massive effective magnetic fields by ultrafast spin current injection. Identifying these fields as key to femtosecond rotation, we establish simple practical rules for their maximisation with wide applicability to all magnetised materials. Employing state-of-the-art time-dependent density-functional theory and using the example of chiral magnet, Mn$_3$Sn, we induce ultrafast rotation enough to drive the switching of magnetic order between the six possible non-collinear ground states. We further demonstrate the possibility of undoing this switching by subsequent injection of oppositely polarized spin current. Our findings place chiral anti-ferromagnets as a materials platform for femtosecond N\'eel-vector switching, opening a route towards the manipulation of magnetic matter at ultrafast times.