Anomalous quantum Griffiths singularity in ultrathin crystalline lead films
Anomalous quantum Griffiths singularity in ultrathin crystalline lead films
复制标题
超薄晶体铅薄膜中的反常量子格里菲斯奇点
DOI：
10.1038/s41467-019-11607-w
复制
发表时间：
2019-08-12
影响因子：
16.6
通讯作者：
Wang, Jian
中科院分区：
文献类型：
--
作者：
Liu, Yi;Wang, Ziqiao;Wang, Jian
Superconductor-insulator/metal transition (SIT/SMT) represents a prototype of quantum phase transition, where quantum fluctuation plays a dominant role and dramatically changes the physical properties of low-dimensional superconducting systems. Recent observation of quantum Griffiths singularity (QGS) offers an essential perspective to understand the subtleties of quantum phase transition in two-dimensional superconductors. Here we study the magnetic field induced SMT in ultrathin crystalline Pb films down to ultralow temperatures. The divergent critical exponent is observed when approaching zero temperature quantum critical point, indicating QGS. Distinctively, the anomalous phase boundary of SMT that the onset critical field decreases with decreasing temperatures in low temperature regime distinguishes our observation from previous reports of QGS in various two-dimensional superconductors. We demonstrate that the anomalous phase boundary originates from the superconducting fluctuations in ultrathin Pb films with pronounced spin-orbit interaction. Our findings reveal a novel aspect of QGS of SMT in two-dimensional superconductors with anomalous phase boundary.
