Research: Neutron scattering in the proximate quantum spin liquid α-RuCl3

The Kitaev quantum spin liquid (KQSL) is an exotic emergent state of matter exhibiting Majorana fermion and gauge flux excitations. The magnetic insulator α-RuCl₃ is thought to realize a proximate KQSL. In a collaboration with colleagues from Oak Ridge (USA) and Cambridge (UK), neutron scattering on single crystals of α-RuCl₃ was used to reconstruct dynamical correlations in energy-momentum space. Highly unusual signals were discovered, including a column of scattering over a large energy interval around the Brillouin zone center, which is very stable with temperature. This finding is consistent with scattering from the Majorana excitations of a KQSL. Other, more delicate experimental features can be transparently associated with perturbations to an ideal model. These results encourage further study of this prototypical material and may open a window into investigating emergent magnetic Majorana fermions in correlated materials.

A. Banerjee, J. Yan, J. Knolle, C. A. Bridges, M. B. Stone, M. D. Lumsden, D. G. Mandrus, D. A. Tennant, R. Moessner, S. E. Nagler,
Neutron scattering in the proximate quantum spin liquid α-RuCl_3,
Science 356, 1055 (2017) (arXiv)