Regensburg 2022 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 36: Focus Session: Ultrafast Spin, Lattice and Charge Dynamics of Solids

TT 36.5: Hauptvortrag

Freitag, 9. September 2022, 11:45–12:15, H10

Ultrafast magnetism of antiferromagnets — •Alexey Kimel — Radboud University, Nijmegen, The Netherlands

Antiferromagnets are ideal candidates to reach the THz landmark in data storage with no additional energy costs. However, the lack of a net magnetization in the antiferromagnetic ground state requires exceedingly high magnetic fields to manipulate the spins, hindering even fundamental studies on the control and switching of antiferromagnets. Here we propose an approach to empower THz control of antiferromagnetic order by pushing antiferromagnet out of equilibrium through a generation of coherent magnonic states. We will show that an antiferromagnet out of equilibrium is practically a different material. Generation of coherent magnonic states in antiferromagnets substantially modifies the susceptibility of antiferromagnetic spins to THz magnetic fields and facilitates energy transfer between otherwise noninteracting phononic and magnonic modes [1,2]. In this case, the generated impact on spins goes far beyond trivial superposition of excitations and can facilitate conceptually new ways for controlling antiferromagnetism. The proposed theoretical description suggests that spin dynamics in antiferromagnets is intrinsically non-linear and once coherent magnonic state is induced, additional channels of energy transfer between otherwise orthogonal modes open up.

[1] E. A. Mashkovich, K. Grishunin, R. Dubrovin, R. V. Pisarev, A. K. Zvezdin and A. V. Kimel, Science 374, 1608 (2021)

[2] Th. Blank et al. (in preparation)