Topological Magnon Bands in a Kagome Lattice Ferromagnet

R. Chisnell, J. S. Helton, D. E. Freedman, D. K. Singh, R. I. Bewley, D. G. Nocera, Y. S. Lee

Research output: Contribution to journalArticlepeer-review

186 Scopus citations

Abstract

There is great interest in finding materials possessing quasiparticles with topological properties. Such materials may have novel excitations that exist on their boundaries which are protected against disorder. We report experimental evidence that magnons in an insulating kagome ferromagnet can have a topological band structure. Our neutron scattering measurements further reveal that one of the bands is flat due to the unique geometry of the kagome lattice. Spin wave calculations show that the measured band structure follows from a simple Heisenberg Hamiltonian with a Dzyaloshinkii-Moriya interaction. This serves as the first realization of an effectively two-dimensional topological magnon insulator - a new class of magnetic material that should display both a magnon Hall effect and protected chiral edge modes.

Original languageEnglish (US)
Article number147201
JournalPhysical review letters
Volume115
Issue number14
DOIs
StatePublished - Sep 28 2015

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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