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MA: Fachverband Magnetismus

MA 9: Altermagnets I

MA 9.10: Vortrag

Montag, 17. März 2025, 17:30–17:45, H20

Altermagnetic spin wave dispersion in atomistic spin models — •Tobias Dannegger¹, Levente Rózsa^2,3, László Szunyogh³, and Ulrich Nowak¹ — ¹Fachbereich Physik, Universität Konstanz, Konstanz, Germany — ²Department of Theoretical Solid State Physics, Institute for Solid State Physics and Optics, HUN-REN Wigner Research Centre for Physics, Budapest, Hungary — ³Department of Theoretical Physics, Institute of Physics, Budapest University of Technology and Economics, Budapest, Hungary

Altermagnets have a broken symmetry reflected in the shape of the spin density around the magnetic atoms. Using an ab initio parametrised atomistic spin model of hematite (α-Fe₂O₃), we show that this altermagnetic symmetry breaking induces a remarkably high splitting of 2.8 meV in the isotropic exchange couplings between the Fe spins for equidistant neighbours within the thirteenth coordination shell. We further study the resulting spin-wave dispersion relation and find that, in addition to the relativistic band splitting on the order of 10 GHz present almost throughout the entire Brillouin zone, the altermagnetic asymmetry of the isotropic interactions causes a much larger band splitting of the order of 1 THz, but only along low-symmetry directions in the Brillouin zone.

Keywords: hematite; dispersion relation; magnon band splitting