The TRR 227 kindly invites you to a special TRR 227 Seminar.

Speaker: Prof. Dr. Mathias Kläui, Institute of Physics, Johannes Gutenberg-Universität Mainz, Germany & Centre for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, Trondheim, Norway

Title:

From antiferromagnets to altermagnets: functionalizing novel magnetic phases

Abstract

While known for a long time, antiferromagnetically ordered systems have previously been considered, as “interesting but useless”. However, since antiferromagnets potentially promises faster operation, enhanced stability and higher integration densities, they could potentially become a game changer for new spintronic devices. Here we show how antiferromagnets can be used as active spintronics devices by demonstrating the key operations of “reading” [1], “writing” [2], and “transporting information” [3] in antiferromagnets.

Going beyond antiferromagnets, we develop altermagnetic materials [4,5]. This recently identified class magnets with collinear antiferromagnetic magnetic order can exhibit spin splitting and particular spin transport properties and torques [4]. Here we demonstrate the spin splitting in RuO₂ and CrSb [5] und analyze particular symmetries of the Hall signal in the altermagnet hematite [6].

[1] S. Bodnar et al., Nat. Commun. 9, 348 (2018); S. Bommanaboyena et al., Nat. Commun. 12, 6539 (2021)

[2] H. Meer et al., Nano Lett. 21, 114 (2020); S. P. Bommanaboyena et al., Nat. Commun. 12, 6539 (2021); C. Schmitt et al., Nano Lett. 24, 1471 (2024)

[3] R. Lebrun et al., Nature 561, 222 (2018). R. Lebrun et al., Nat. Commun. 11, 6332 (2020). S. Das et al., Nat. Commun. 13, 6140 (2022)

[4] L. Smejkal et al., Phys. Rev. X 12, 040501 (2022)

[5] O. Fedchenko et al., Sci Adv. 10, adj4883 (2024); S. Reimers et al., Nat. Commun. 15, 2116 (2024)

[6] E. Galindez-Ruales et al., arxiv:2310.16907