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TT: Fachverband Tiefe Temperaturen

TT 53: Topology: Other Topics

TT 53.2: Vortrag

Freitag, 21. März 2025, 09:45–10:00, H32

Theory of Quantum Geometry in Unconventional Magnets — •Johannes Mitscherling, Jan Priessnitz, and Libor Smejkal — Max Plank Institute for the Physics of Complex Systems, Nöthnitzer Str. 38, 01187 Dresden, Germany

Metals with altermagnetic spin-polarisation [1] and non-collinear spin textures [2] are emerging platforms exhibiting rich fundamental physics and spintronics applications. Remarkably, this class of materials intrinsically yields a complex interplay of at least two orbital degrees of freedom besides spin. It was recently noticed that such multiband Hamiltonians host previously overlooked geometric invariants beyond the quantum metric and Berry curvature, especially when more than two bands are involved, making altermagnetic and non-collinear magnetic systems promising candidates for novel quantum geometric responses [3]. In this talk, I will introduce a quantum geometric perspective adequate for multiband systems with both spin and orbital degrees of freedom, which helps us to determine and quantify the properties of the nontrivial Bloch states. With this systematic geometric characterization, I will elaborate on a pathway to identify the most promising observables, model parameter regimes, and tuning parameters, simplifying the search for experimental realizations.

[1] L. Smejkal, J. Sinova, T. Jungwirth, PRX 12, 031042 (2022).

[2] A. Birk Hellenes, T. Jungwirth, R. Jaeschke-Ubiergo,
A. Chakraborty, J. Sinova, L. Smejkal, arXiv:2309.01607v3.

[3] A. Avdoshkin, J. Mitscherling, J. E. Moore, arXiv:2409.16358.

Keywords: Quantum geometry; Unconventional magnets; Beyond quantum metric and Berry curvature; Altermagnets; Non-collinear magnetic textures