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Neutron Spectroscopy Evidence for a Possible Magnetic-Field-Induced Gapless Quantum-Spin-Liquid Phase in a Kitaev Material α-RuCl3

Zhao, Xiaoxue; Ran, Kejing; Wang, Jinghui; Bao, Song; Shangguan, Yanyan; Huang, Zhentao; Liao, Junbo; Zhang, Bo; Cheng, Shufan; Xu, Hao; Wang, Wei; Dong, Zhao-Yang; Meng, Siqin; Lu, Zhilun; Yano, Shin-ichiro; Yu, Shun-Li; Li, Jian-Xin; Wen, Jinsheng


Xiaoxue Zhao

Kejing Ran

Jinghui Wang

Song Bao

Yanyan Shangguan

Zhentao Huang

Junbo Liao

Bo Zhang

Shufan Cheng

Hao Xu

Wei Wang

Zhao-Yang Dong

Siqin Meng

Zhilun Lu

Shin-ichiro Yano

Shun-Li Yu

Jian-Xin Li

Jinsheng Wen


As one of the most promising Kitaev quantum-spin-liquid (QSL) candidates, α-RuCl3 has received a great deal of attention. However, its ground state exhibits a long-range zigzag magnetic order, which defies the QSL phase. Nevertheless, the magnetic order is fragile and can be completely suppressed by applying an external magnetic field. Here, we explore the evolution of magnetic excitations of α-RuCl3 under an in-plane magnetic field, by carrying out inelastic neutron scattering measurements on high-quality single crystals. Under zero field, there exist spin-wave excitations near the M point and a continuum near the Γ point, which are believed to be associated with the zigzag magnetic order and fractional excitations of the Kitaev QSL state, respectively. By increasing the magnetic field, the spin-wave excitations gradually give way to the continuous excitations. On the verge of the critical field μ0Hc = 7.5 T, the former ones vanish and only the latter ones are left, indicating the emergence of a pure QSL state. By further increasing the field strength, the excitations near the Γ point become more intense. By following the gap evolution of the excitations near the Γ point, we are able to establish a phase diagram composed of three interesting phases, including a gapped zigzag order phase at low fields, possibly gapless QSL phase near μ0Hc, and gapped partially polarized phase at high fields. These results demonstrate that an in-plane magnetic field can drive α-RuCl3 into a long-sought QSL state near the critical field.

Journal Article Type Article
Acceptance Date Apr 2, 2022
Online Publication Date Apr 5, 2022
Publication Date 2022-04
Deposit Date May 2, 2022
Publicly Available Date Apr 6, 2023
Journal Chinese Physics Letters
Print ISSN 0256-307X
Electronic ISSN 1741-3540
Publisher IOP Publishing
Peer Reviewed Peer Reviewed
Volume 39
Issue 5
Article Number 057501
Public URL


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