Unconventional magnetic oscillations in a kagome Mott insulator
Guoxin Zheng, Yuan Zhu, Kuan‐Wen Chen, Byungmin Kang, Dechen Zhang, Kaila Jenkins, Aaron Chan, Zhenyuan Zeng, Aini Xu, O. Ayala Valenzuela, Joanna Bławat, John Singleton, Shiliang Li, Patrick A. Lee, Lü Li
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 an 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 [Formula: see text] 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.