title: Quantum Griffiths singularity of superconductor-metal transition in Ga thin films.
abstract: The Griffiths singularity in a phase transition, caused by disorder effects, was predicted more than 40 years ago. Its signature, the divergence of the dynamical critical exponent, is challenging to observe experimentally. We report the experimental observation of the quantum Griffiths singularity in a two-dimensional superconducting system. We measured the transport properties of atomically thin gallium films and found that the films undergo superconductor-metal transitions with increasing magnetic field. Approaching the zero-temperature quantum critical point, we observed divergence of the dynamical critical exponent, which is consistent with the Griffiths singularity behavior. We interpret the observed superconductor-metal quantum phase transition as the infinite-randomness critical point, where the properties of the system are controlled by rare large superconducting regions.
authors.affiliation: International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Xing
authors.affiliation: Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Hui-Min
authors.initials: HM
authors.lastname: Zhang
authors.affiliation: International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China.
authors.forename: Hai-Long
authors.initials: HL
authors.lastname: Fu
authors.affiliation: International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China. Collaborative Innovation Center of Quantum Matter, Beijing, China.
authors.forename: Haiwen
authors.initials: H
authors.lastname: Liu
authors.affiliation: International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Jun-Ping
authors.initials: JP
authors.lastname: Peng
authors.affiliation: International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China. Collaborative Innovation Center of Quantum Matter, Beijing, China.
authors.forename: Fa
authors.initials: F
authors.lastname: Wang
authors.affiliation: International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China. Collaborative Innovation Center of Quantum Matter, Beijing, China. jianwangphysics@pku.edu.cn xucunma@mail.tsinghua.edu.cn xilin@pku.edu.cn.
authors.forename: Xi
authors.initials: X
authors.lastname: Lin
authors.affiliation: Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China. State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China. Collaborative Innovation Center of Quantum Matter, Beijing, China. jianwangphysics@pku.edu.cn xucunma@mail.tsinghua.edu.cn xilin@pku.edu.cn.
authors.forename: Xu-Cun
authors.initials: XC
authors.lastname: Ma
authors.affiliation: State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China. Collaborative Innovation Center of Quantum Matter, Beijing, China.
authors.forename: Qi-Kun
authors.initials: QK
authors.lastname: Xue
authors.affiliation: International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China. Collaborative Innovation Center of Quantum Matter, Beijing, China. jianwangphysics@pku.edu.cn xucunma@mail.tsinghua.edu.cn xilin@pku.edu.cn.
authors.forename: Jian
authors.initials: J
authors.lastname: Wang
authors.affiliation: International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China. Collaborative Innovation Center of Quantum Matter, Beijing, China.
authors.forename: X C
authors.initials: XC
authors.lastname: Xie