Fig. 4

Schematic of the B–T phase diagram of two-dimensional superconductor–metal transition (SMT) with pronounced fluctuation effect. B₂ is the value of upper critical field with mean field theory. Under the influence of superconducting fluctuations with strong spin–orbit interaction, the mean field phase boundary (blue dashed line) buckles outward to the solid red line, which gives rise to the reentrant phenomena shown in Figs. 1b and 3a. The anomalous phase boundary exists in the regime \([B_{\mathrm{c}}^ \ast ,B_{\mathrm{c}}^\prime ]\). When approaching the real infinite-randomness quantum critical point \(B_{\mathrm{c}}^ \ast\) along this anomalous phase boundary, the system exhibits anomalous quantum Griffiths singularity behavior