Néel vector switching and terahertz spin-wave excitation in Mn2Au due to femtosecond spin-transfer torques

Efficient and fast manipulation of antiferromagnets has to date remained a challenging task, hindering their application in spintronic devices. For ultrafast operation of such devices, it is highly desirable to be able to control the antiferromagnetic order within picoseconds-a timescale that is difficult to achieve with electrical circuits. Here, we demonstrate that bursts of spin-polarized hot-electron currents emerging due to laser-induced ultrafast demagnetization are able to efficiently excite spin dynamics in antiferromagnetic Mn2Au by exerting a spintransfer torque on femtosecond timescales. We combine quantitative superdiffusive transport and atomistic spinmodel calculations to describe a spin-valve-type trilayer consisting of Fe|Cu|Mn2Au. Our results demonstrate that femtosecond spin-transfer torques can switch the Mn2Au layer within a few picoseconds. In addition, we find that spin waves with high frequencies up to several THz can be excited in Mn2Au.