Kavli Affiliate: Jia Liu
| First 5 Authors: Jia Liu, Long Cheng, Junkun Zha, Fei Ye, Xiaofang Zhai
| Summary:
In two-dimensional (2D) limit, the quantum fluctuation is significantly
enhanced which could induce a quantum phase transition. Investigating the
quantum criticality is an effective approach to elucidate the underlying
physics of 2D superconductivity. Here we report the observation of different
universality classes of quantum criticality at the superconducting
LaAlO$_3$/KTaO$_3$ (111) interface, i.e. the normal quantum Griffiths
singularity (QGS) and the anomalous QGS. The switch of the quantum criticality
class is observed from the normal QGS in a low $T_c$ sample with weaker
spin-orbit coupling (SOC) to the anomalous QGS in a high $T_c$ sample with
stronger SOC. Moreover, owing to the remarkable SOC strength, the high $T_c$
sample exhibits an unprecedentedly enhanced quantum fluctuation at an unusually
elevated temperature approaching the Berezinskii-Kosterlitz-Thouless (BKT)
transition temperature $T_{BKT}$. This work provides comprehensive recognition
of the different quantum criticality classes in the same superconducting
LaAlO$_3$/KTaO$_3$ (111) system, which deepens the understanding of the
superconducting mechanism of interfacial superconductors.
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