Unconventional Magnetic Oscillations in Kagome Mott Insulators

Authors:
  • GZGuoxin Zheng
    Guoxin Zheng
  • YZYuan Zhu
    Yuan Zhu
  • KCKuan-Wen Chen
    Kuan-Wen Chen
  • BKByungmin Kang
    Byungmin Kang
  • DZDechen Zhang
    Dechen Zhang
  • KJKaila Jenkins
    Kaila Jenkins
  • ACAaron Chan
    Aaron Chan
  • ZZZhenyuan Zeng
    Zhenyuan Zeng
  • AXAini Xu
    Aini Xu
  • OVOscar A. Valenzuela
    Oscar A. Valenzuela
  • JBJoanna Blawat
    Joanna Blawat
  • JSJohn Singleton
    John Singleton
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Abstract
In metals, electrons in a magnetic field undergo cyclotron motion, leading to oscillations in physical properties called quantum oscillations. This phenomenon has never been seen in a robust insulator because there are no mobile electrons. We report the first exception to this rule. We study a Mott insulator on a kagome lattice which does not order magnetically down to milli-Kelvin temperatures despite antiferromagnetic interactions. We observe a plateau at magnetization equal to 1/9 Bohr magneton per magnetic ion, accompanied by oscillations in the magnetic torque, reminiscent of quantum oscillations in metals. The temperature dependence obeys Fermi distribution. These phenomena are consistent with a quantum spin liquid state whose excitations are fermionic spinons with a Dirac-like spectrum coupled to an emergent gauge field.