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Journal Article

Proximate spin liquid and fractionalization in the triangular antiferromagnet KYbSe2

The Heisenberg triangular-lattice quantum spin liquid and its phase transitions to nearby magnetic orders have received much theoretical attention, but clear experimental manifestations of these states are rare. Here we demonstrate that a spin-half delafossite material, namely, KYbSe2, shows close proximity to the triangular-lattice Heisenberg quantum spin liquid. Using neutron scattering, we identify a diffuse continuum with a sharp lower bound within the measured spectra. Applying entanglement witnesses to the data indicates multipartite entanglement spread between its neighbours, and an analysis of its magnetic-exchange couplings reveals close proximity to the theoretical quantum spin-liquid phase. The key features of the data are reproduced by Schwinger boson theory and tensor network calculations with a substantial next-nearest-neighbour coupling. The strength of the dynamical structure factor at the Brillouin-zone K point shows a scaling collapse down to 0.3 K, indicating the existence of a second-order quantum phase transition. Comparing this with previous theoretical work suggests that the proximate phase at a larger next-nearest-neighbour coupling is a gapped Z2 spin liquid, resolving a long-debated issue.

Author(s)
A. Scheie
E. A. Ghioldi
J. Xing
J. A. M. Paddison
N. E. Sherman
M. Dupont
D. Abernathy
D. Pajerowski
Shang-Shun Zhang
L. O. Manuel
A. E. Trumper
C. D. Pemmaraju
D. S. Parker
T. P. Devereaux
J.E. Moore
C. D. Batista
D. A. Tennant
Journal Name
Nature Physics
Publication Date
November 6, 2023
DOI
10.1038/s41567-023-02259-1