Prof. Dr. Jure Demšar (JGU Mainz): Optical read-out and manipulation of Néel vector in a metallic antiferromagnet

Datum objave: 19. 5. 2022
Ponedeljkov fizikalni kolokvij
16.15 - 17.15
ID: 980 0889 5298
V ponedeljek, 23. 5. 2022, ob 16:15 prek Zooma

The absence of stray fields, their robustness against external magnetic fields, and the inherently fast dynamics make antiferromagnets promising candidates for active elements in spintronic devices [1]. Especially the metallic collinear antiferromagnets CuMnAs and Mn2Au, which enable current-driven bulk (Néel) spin-orbit torques [2] have been in the research focus recently. The lack of sensitivity to external magnetic fields, however, poses challenges in terms of manipulation and read-out of the staggered magnetization (Néel vector). Thus, while ultrafast optical control of magnetization in several ferro- and ferri-magnets has been demonstrated in recent years [3-5], such approaches in antiferromagnets are scarse. Here, we address the optical read-out in a metallic collinear antiferromagnet Mn2Au [6] and present an approach of its optical manipulation by combining tensile strain and excitation with femtosecond optical pulses [7]. The dependence of switching on the laser fluence and strain suggests the Néel vector alignment is a result of optically-triggered depinning of 90o domain walls and their sliding in the direction governed by the magneto-elastic coupling. The switched, metastable, state is stable at room temperature and insensitive to magnetic fields. Thus, this approach may provide ways to realize robust high-density memory device with switching timescales in the picosecond range.
[1] P. Nemec, M. Fiebig, T. Kampfrath, A.V. Kimel, Nat. Phys. 14, 229–241 (2018).
[2] J. Železny, et al., Phys. Rev. Lett. 113, 157201 (2014).
[3] A. Kimel, et al., Nature 435, 655–657 (2005).
[4] A. R. Khorsand, et al., Phys. Rev. Lett. 108, 127205 (2012).
[5] C.-H. Lambert, et al., Science 345, 1337–1340 (2014).
[6] V. Grigorev, et al., Phys. Rev. Appl. 16, 014037 (2021).
[7] V. Grigorev, et al., arXiv:2205.05411.