Topological Spin Excitations in Honeycomb Ferromagnet CrI3

Lebing Chen, Jae Ho Chung, Bin Gao, Tong Chen, Matthew B. Stone, Alexander I. Kolesnikov, Qingzhen Huang, Pengcheng Dai

Research output: Contribution to journalArticlepeer-review

211 Citations (Scopus)


In two-dimensional honeycomb ferromagnets, bosonic magnon quasiparticles (spin waves) may either behave as massless Dirac fermions or form topologically protected edge states. The key ingredient defining their nature is the next-nearest-neighbor Dzyaloshinskii-Moriya interaction that breaks the inversion symmetry of the lattice and discriminates chirality of the associated spin-wave excitations. Using inelastic neutron scattering, we find that spin waves of the insulating honeycomb ferromagnet CrI3 (TC=61 K) have two distinctive bands of ferromagnetic excitations separated by a ∼4 meV gap at the Dirac points. These results can only be understood by considering a Heisenberg Hamiltonian with Dzyaloshinskii-Moriya interaction, thus providing experimental evidence that spin waves in CrI3 can have robust topological properties potentially useful for dissipationless spintronic applications.

Original languageEnglish
Article number041028
JournalPhysical Review X
Issue number4
Publication statusPublished - 2018 Nov 14

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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