Antiferromagnets have large potential for ultrafast coherent switching of magnetic order with minimum heat dissipation. In materials such as Mn2Au and CuMnAs, electric rather than magnetic fields may control antiferromagnetic order by Néel spin-orbit torques (NSOTs). However, these torques have not yet been observed on ultrafast time scales. Here, we excite Mn2Au thin films with phase-locked single-cycle terahertz electromagnetic pulses and monitor the spin response with femtosecond magneto-optic probes. We observe signals whose symmetry, dynamics, terahertz-field scaling and dependence on sample structure are fully consistent with a uniform in-plane antiferromagnetic magnon driven by field-like terahertz NSOTs with a torkance of (150 ± 50) cm2 A−1 s−1. At incident terahertz electric fields above 500 kV cm−1, we find pronounced nonlinear dynamics with massive Néel-vector deflections by as much as 30°. Our data are in excellent agreement with a micromagnetic model. It indicates that fully coherent Néel-vector switching by 90° within 1 ps is within close reach.
Bibliographical noteKAUST Repository Item: Exported on 2023-10-02
Acknowledged KAUST grant number(s): OSR-2019-CRG8-4048
Acknowledgements: Open Access funding enabled and organized by Projekt DEAL. We acknowledge funding by the German Research Foundation through the collaborative research centers SFB TRR 227 “Ultrafast spin dynamics” (project ID 328545488, projects A05 and B02) [Y.B., A.L.C., O.Gue., T.S.S., T.K.], SFB TRR 173 “Spin+X” (project ID 268565370, projects A01, A05, A11, B02 and B12) [S.Y.B., S.R., Y.L., O.Go., M.K., M.J.] and priority program SPP2314 INTEREST (project ITISA) [Y.B., A.L.C., O.Gue., T.S.S., T.K.], the European Union through the projects ERC H2020 CoG TERAMAG/grant no. 681917 [Y.B., A.L.C., O.Gue., T.S.S., T.K.] and ERC SyG 3D MAGiC/grant no. 856538 [S.Y.B., S.R., Y.L., M.K., M.J.]. We acknowledge KAUST (Grant No. OSR-2019-CRG8-4048) [S.Y.B., S.R., Y.L., M.K., M.J.] and support by the European Commission under FET-Open Grant Agreements No. 863155 (s-Nebula) [Y.B., A.L.C., O.Gue., T.S.S., T.K., S.Y.B., S.R., Y.L., M.K., M.J.] and No. 766566 (ASPIN) [S.Y.B., S.R., Y.L., O.Go., M.K., M.J.] and No. 101070287 (SWAN-on-chip) [M.K., M.J., S.R.].
This publication acknowledges KAUST support, but has no KAUST affiliated authors.
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)
- Physics and Astronomy(all)