TY  - JOUR
PB  - SciPost Foundation
DO  - 10.21468/SciPostPhys.17.2.066
TI  - Mean-field theory of first-order quantum superconductor-insulator transition
PY  - 2024/08/23
UR  - https://scipost.org/SciPostPhys.17.2.066
JF  - SciPost Physics
JA  - SciPost Phys.
VL  - 17
IS  - 2
SP  - 066
A1  - Poboiko, Igor
AU  - Feigel'man, Mikhail V.
AB  - Recent experimental studies on strongly disordered indium oxide films have revealed an unusual first-order quantum phase transition between the superconducting and insulating states (SIT). This transition is characterized by a discontinuous jump from non-zero to zero values of superfluid stiffness at the critical point, contradicting the conventional "scaling scenario" typically associated with SIT. In this paper, we present a theoretical framework for understanding this first-order transition. Our approach is based on the concept of competition between two fundamentally distinct ground states that arise from electron pairs initially localized by strong disorder: the superconducting state and the Coulomb glass insulator. These ground states are distinguished by two crucially different order parameters, suggesting a natural expectation of a discontinuous transition between them at $T=0$. This transition occurs when the magnitudes of the superconducting gap $\Delta$ and the Coulomb gap $E_C$ become comparable. Additionally, we extend our analysis to low non-zero temperatures and provide a mean-field "phase diagram" in the plane of $(T/\Delta,E_C/\Delta)$. Our results reveal the existence of a natural upper bound for the kinetic inductance of strongly disordered superconductors.
ER  -

@Article{10.21468/SciPostPhys.17.2.066,
	title={{Mean-field theory of first-order quantum superconductor-insulator transition}},
	author={Igor Poboiko and Mikhail Feigel'man},
	journal={SciPost Phys.},
	volume={17},
	pages={066},
	year={2024},
	publisher={SciPost},
	doi={10.21468/SciPostPhys.17.2.066},
	url={https://scipost.org/10.21468/SciPostPhys.17.2.066},
}