SKM 2021 – scientific programme

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MA: Fachverband Magnetismus

MA 15: Posters Magnetism IV

MA 15.9: Poster

Thursday, September 30, 2021, 13:30–16:30, P

Efficient spin excitation via ultrafast damping torques in antiferromagnets — •Christian Tzschaschel^1,2, Takuya Satoh³, and Manfred Fiebig¹ — ¹Department of Materials, ETH Zurich, Switzerland — ²Department of Chemistry and Chemical Biology, Harvard University, USA — ³Department of Physics, Tokyo Institute of Technology, Japan

Damping effects form the core of many emerging concepts for high-speed spintronic applications. Important characteristics such as device switching times and magnetic domain-wall velocities depend critically on the damping rate. While the implications of spin damping for relaxation processes are intensively studied, damping effects during impulsive spin excitations are assumed to be negligible because of the shortness of the excitation process. Here we show that, unlike in ferromagnets, ultrafast damping plays a crucial role in antiferromagnets because of their strongly elliptical spin precession. In time-resolved measurements, we find that ultrafast damping results in an immediate spin canting along the short precession axis. The interplay between antiferromagnetic exchange and magnetic anisotropy amplifies this canting by several orders of magnitude towards large-amplitude modulations of the antiferromagnetic order parameter. Exemplarily, we consider optical spin excitations in antiferromagnetic hexagonal RMnO₃ via the inverse Faraday effect. We find that a so far overlooked damping torque can even provide the dominant excitation mechanism. We thus disclose a highly efficient route towards the ultrafast manipulation of magnetism in antiferromagnetic spintronics.