Jeffrey G. Rau : Chiral magnons in insulating altermagnets: Symmetries and experimental signatures
Jeffrey G. Rau, University of Windsor, Canada
Le résumé :
Altermagnets, a new class of magnetic systems that combine characteristics of both conventional ferromagnets and antiferromagnets, have recently attracted significant attention. These collinear compensated magnets exhibit spin-split bands even in the absence of spin-orbit coupling, offering exciting prospects for applications in antiferromagnetic spintronics due to their lack of stray fields, low damping and fast switching times.
I will give a pedagogical introduction to altermagnets from a symmetry-based perspective, focusing on the insulating case and its magnetic excitations. I will discuss how due to an approximate U(1) symmetry the magnons in altermagnets are split into equal and opposite chiral pairs with the anisotropy of the chirality splitting mirroring the splitting of the electronic bands. I will argue that in altermagnets polarized neutrons provide a means to detect the population of time-reversed domains and allow direct measurement of the magnon chirality anisotropy in momentum space – the central signature of the altermagnetic phase. We demonstrate this response to polarized neutrons theoretically in two candidate materials MnF2 and MnTe and show that the presence of these chiralities is stable to small perturbations that break spin-rotation symmetry.
Finally, I will discuss challenges in observing these features experimentally and how to distinguish between altermagnetic and relativistic splittings.