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

• 作者: 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
• 来源期刊: 中国物理快报（英文版）
• 年，卷（期）: 2022,（5）
• 所属期刊栏目: CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL MAGNETIC, AND OPTICAL PROPERTIES
• 页码范围: 146-154
• 页数: 9页
• 语种: 英文
• DOI: 10.1088/0256-307X/39/5/057501

摘要

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 T 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 Г point become more intense.By following the gap evolution of the excitations near the Г 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.