biostudies-literatureUnknown10(1)Liu YSuperconductor-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 regimNature communications3633https://www.ebi.ac.uk/biostudies/studies/S-EPMC6690870biostudies-literatureAnomalous quantum Griffiths singularity in ultrathin crystalline lead films.PMC6690870Liu HLiu YWang QXing YXie XCLin XShan PLiu CChen CWang ZWang JTang YfalseAnomalous quantum Griffiths singularity in ultrathin crystalline lead films.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 regim2019-01-01T00:00:00Z2019 Aug2025-04-04T19:02:57.986Z2019-08-20T07:04:51ZS-EPMC66908703140611410.1038/s41467-019-11607-w