Abstract:

Quantum spin liquid is a novel magnetic state without long-range order even at zero temperature due to strong quantum fluctuations. The ground state of quantum spin liquid cannot be described by order parameters, and there is no symmetry breaking in this exotic state, which means that the realization of quantum spin liquid states will break through the paradigm of Landau’s theory. Studies on quantum spin liquid will be helpful for the understanding of the mechanism of high-temperature superconductivity and the application of quantum calculation and quantum information. Although there are many advances in the theory, no material is confirmed to be a real quantum spin liquid so far, making it important to realize a quantum spin liquid material and confirm its properties. Muon spin relaxation, a powerful technique that is extremely sensitive to magnetic fields, has been widely used in the study of quantum spin liquid candidates. Muon spin relaxation can observe whether there is long-range order in the ground state, and measure the fluctuation rate in the system, both of which are the basic properties of quantum spin liquid. This article gives a brief introduction to the quantum spin liquid state and muon spin relaxation technique. Then recent experimental works, especially muon spin relaxation experiments, on different systems, including one-dimensional antiferromagnetic Heisenberg chain (copper benzoate), triangular lattice (YbMgGaO₄, NaYbO₂ and TbInO₃), kagomè lattice [ZnCu₃(OH)₆Cl₂ and Tm₃Sb₃Zn2O₁₄], honeycomb lattice (Na₂IrO₃ and α-RuCl3) and pyrochlore lattice (Tb₂Ti₂O₇, Pr₂Ir₂O₇ and Ce₂Zr₂O₇) are reviewed.

Key words: Strongly-Correlated System, μSR, Quantum Spin Liquid