Speaker: Maxim Khodas , Hebrew University of Jerusalem
Abstract: I begin with a general exposition of altermagnetism, introducing the two-dimensional Lieb lattice as the simplest realization of this novel magnetic phase. The anomalous Hall effect arising from altermagnetic order and spin–orbit interaction is discussed based on symmetry considerations and illustrated with several examples. A comparison between the magnetic point-group and spin-space-group formulations is presented, demonstrating that the Berry-curvature singularity at nodal lines gives rise to a linear, non-analytic scaling of the intrinsic Hall conductivity with spin–orbit coupling.
In the second part of the talk, I consider the extrinsic anomalous Hall effect in the limit of large exchange splitting. In materials with a finite Dzyaloshinskii–Moriya–type interaction, the extrinsic contribution remains essential even in the clean limit. This naturally separates altermagnetic symmetry classes into two distinct categories, differing from other classifications found in the literature.