Majorana fermions in the Kitaev quantum spin system α-RuCl 3

Seung Hwan Do, Sang Youn Park, Junki Yoshitake, Joji Nasu, Yukitoshi Motome, Yong Seung Kwon, D. T. Adroja, D. J. Voneshen, Kyoo Kim, T. H. Jang, J. H. Park, Kwang Yong Choi, Sungdae Ji

Research output: Contribution to journalArticlepeer-review

223 Citations (Scopus)


Geometrical constraints to the electronic degrees of freedom within condensed-matter systems often give rise to topological quantum states of matter such as fractional quantum Hall states, topological insulators, and Weyl semimetals. In magnetism, theoretical studies predict an entangled magnetic quantum state with topological ordering and fractionalized spin excitations, the quantum spin liquid. In particular, the so-called Kitaev spin model, consisting of a network of spins on a honeycomb lattice, is predicted to host Majorana fermions as its excitations. By means of a combination of specific heat measurements and inelastic neutron scattering experiments, we demonstrate the emergence of Majorana fermions in single crystals of α-RuCl 3, an experimental realization of the Kitaev spin lattice. The specific heat data unveils a two-stage release of magnetic entropy that is characteristic of localized and itinerant Majorana fermions. The neutron scattering results corroborate this picture by revealing quasielastic excitations at low energies around the Brillouin zone centre and an hour-glass-like magnetic continuum at high energies. Our results confirm the presence of Majorana fermions in the Kitaev quantum spin liquid and provide an opportunity to build a unified conceptual framework for investigating fractionalized excitations in condensed matter.

Original languageEnglish
Pages (from-to)1079-1084
Number of pages6
JournalNature Physics
Issue number11
Publication statusPublished - 2017 Nov 1
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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