Materials Science and Engineering Weekly Seminar with Dr. Mathias Kläui

Mathias Kläui with curly hair and glasses, wearing a dark blazer and light blue shirt.

Event Date

Location
1062 Bainer Hall

Combining The Best Of All Worlds: Altermagnets – A New Class Of Magnets

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 start by showing 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 of magnets with collinear antiferromagnetic magnetic order combines the best of antiferromagnets and ferromagnets, exhibiting 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 where we can also quantify altermagnetic domains by XMCD & XMLD imaging [6].

Finally, we show that the spin splitting also manifests in the magnonic band structure, leading to altermagnetic spin transport in insulating d-wave altermagnets [7].

Reference

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

[2] H. Meer et al., Nano Lett. 21, 114 (2020); S. P. Bommanaboyena et al., Nature 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., Nature Commun. 11, 6332 (2020). S. Das et al., Nature 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., Nature Commun. 15, 2116 (2024).

[6] E. Galindez-Ruales et al., Adv. Mater. 37, e05019 (2025).

[7] E. Galindez-Ruales et al., arxiv :2508.14569.

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