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Title: Weyl magnons in breathing pyrochlore antiferromagnets

Frustrated quantum magnets not only provide exotic ground states and unusual magnetic structures, but also support unconventional excitations in many cases. Using a physically relevant spin model for a breathing pyrochlore lattice, we discuss the presence of topological linear band crossings of magnons in antiferromagnets. These are the analogues of Weyl fermions in electronic systems, which we dub Weyl magnons. The bulk Weyl magnon implies the presence of chiral magnon surface states forming arcs at finite energy. We argue that such antiferromagnets present a unique example, in which Weyl points can be manipulated in situ in the laboratory by applied fields. We discuss their appearance specifically in the breathing pyrochlore lattice, and give some general discussion of conditions to find Weyl magnons, and how they may be probed experimentally. Our work may inspire a re-examination of the magnetic excitations in many magnetically ordered systems.
 [1] ; ORCiD logo [2] ;  [3] ;  [4] ;  [5] ;  [5]
  1. Chinese Academy of Sciences (CAS), Beijing (China). Inst. of Theoretical Physics
  2. Fudan Univ., Shanghai (China). School of Computer Science
  3. Univ. of Toronto, ON (Canada). Canadian Inst. for Advanced Research, Dept. of Physics
  4. Univ. of California, Santa Barbara, CA (United States). Kavli Inst. for Theoretical Physics
  5. Fudan Univ., Shanghai (China). State Key Lab. of Surface Physics and Dept. of Physics; Fudan Univ., Shanghai (China). Center for Field Theory and Particle Physics, Dept. of Physics; Collaborative Innovation Center of Advanced Microstructures, Nanjing (China)
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Nature Communications
Additional Journal Information:
Journal Volume: 7; Journal ID: ISSN 2041-1723
Nature Publishing Group
Research Org:
Univ. of California, Santa Barbara, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
36 MATERIALS SCIENCE; Electronic properties and materials; Magnetic properties and materials; Topological insulators
OSTI Identifier: