In this work, the quantum Griffiths singularity (QGS) of superconductor-insulator transition (SIT) is discovered in TiO thin films with insulating normal states. A magnetic field-tuned SIT with a diverging dynamic critical exponent, the direct evidence of QGS, is observed in TiO thin films with different thicknesses. The critical magnetic field Hc tends to saturate at low temperature, different from the upturn trend of Hc in superconductor-metal transition (SMT) systems. The results extend the QGS scenario from SMT systems to SIT systems, and provide decisive clues to conclude that the QGS is a common feature of crystalline superconducting thin films.
- Chao Zhang
- Yunjie Fan
- Xiaoguang Li
