The activated scaling behavior of quantum Griffiths singularity in two-dimensional superconductors

Abstract

Quantum Griffiths singularity (QGS) is characterized by the divergence of the dynamical critical exponent with the activated scaling law and has been widely observed in various two-dimensional superconductors. Recently, the direct activated scaling analysis with the irrelevant correction was proposed and successfully used to analyze the experimental data of crystalline PdTe2 and polycrystalline -W films, which provides new evidence of QGS. Here we show that the direct activated scaling analysis is applicable to the experimental data in different superconducting films, including tri-layer Ga films and LaAlO3/SrTiO3 interface superconductors. When taking the irrelevant correction into account, we calculate the corrected sheet resistance at ultralow temperatures. The scaling behavior of the corrected resistance in a comparably large temperature regime and the theoretical fitting of the phase boundary give unambiguous evidence of QGS. Compared to previous methods based on finite size scaling, the direct activated scaling analysis represents a more direct and precise way to analyze the experimental data of QGS in diverse two-dimensional superconductors.