Magnon topology driven by altermagnetism

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

  • Subhankar Khatua - , Leibniz Institute for Solid State and Materials Research Dresden, Würzburg-Dresden Cluster of Excellence ctd.qmat (Author)
  • Volodymyr P. Kravchuk - , Leibniz Institute for Solid State and Materials Research Dresden, NASU - Bogolyubov Institute for Theoretical Physics, Würzburg-Dresden Cluster of Excellence ctd.qmat (Author)
  • Kostiantyn V. Yershov - , Leibniz Institute for Solid State and Materials Research Dresden, NASU - Bogolyubov Institute for Theoretical Physics (Author)
  • Jeroen van den Brink - , Clusters of Excellence ctd.qmat: Complexity, Topology and Dynamics in Quantum Matter, Chair of Solid State Theory, Leibniz Institute for Solid State and Materials Research Dresden (Author)

Abstract

Altermagnets present a class of fully compensated collinear magnetic order, where the two sublattices are not related merely by time-reversal combined with lattice translation or inversion, but require an additional lattice rotation. This distinctive symmetry leads to a characteristic splitting of the magnon bands; however, the splitting is only partial—residual degeneracies persist along certain lines in the Brillouin zone as a consequence of the underlying altermagnetic rotation. We consider a two-dimensional d-wave altermagnetic spin model on the checkerboard lattice and introduce additional interactions such as an external magnetic field and Dzyaloshinskii-Moriya interactions that lift these degeneracies. The resulting magnon bands become fully gapped and acquire nontrivial topology, characterized by nonzero Chern numbers. We demonstrate the crucial role of altermagnetism for the generation of the Berry curvature. As a direct consequence of the topological magnons, we find finite thermal Hall conductivity κxy, which exhibits a characteristic low-temperature scaling, κxy ∝ T4. Moreover, κxy changes signs under reversal of the magnetic field, exhibiting a sharp jump across zero field at low temperatures. We also demonstrate topologically protected chiral edge modes in a finite strip geometry.

Details

Original languageEnglish
Article number214422
Number of pages16
JournalPhysical Review B
Volume112
Issue number21
Publication statusPublished - 10 Dec 2025
Peer-reviewedYes