Size dependent nature of the magnetic-field driven superconductor-to-insulator quantum-phase transitions

Abstract

The nature of the magnetic-field driven superconductor-to-insulator quantum-phase transition in two-dimensional systems at zero temperature has been under debate since the 1980s, and became even more controversial after the observation of a quantum-Griffiths singularity. Whether it is induced by quantum fluctuations of the superconducting phase and the localization of Cooper pairs, or is directly driven by depairing of these pairs, remains an open question. We herein experimentally demonstrate that in weakly-pinning systems and in the limit of infinitely wide films, a sequential superconductor-to-Bose insulator-to-Fermi insulator quantum-phase transition takes place. By limiting their size smaller than the effective penetration depth, however, the vortex interaction alters, and the superconducting state re-enters the Bose-insulating state. As a consequence, one observes a direct superconductor-to-Fermi insulator in the zero-temperature limit. In narrow films, the associated critical-exponent products diverge along the corresponding phase boundaries with increasing magnetic field, which is a hallmark of the quantum-Griffiths singularity.

6 main figures, 11 supplementary Figures, 2 supplementary Movies. This is a preprint of an article published in Communications Physics. The final authenticated open-access version with updated figures and text is available for free from May 14, 2021 at https://doi.org/10.1038/s42005-021-00602-7

References in corpus (6)

• Electric Field Control of the LaAlO${}_3$/SrTiO${}_3$ Interface Ground State
• Highly crystalline 2D superconductors
• Disorder-Induced Inhomogeneities of the Superconducting State Close to the Superconductor-Insulator Transition
• Quantum breakdown of superconductivity in low-dimensional materials
• Two-stage magnetic-field-tuned superconductor-insulator transition in underdoped La${}_{2-x}$Sr${}_x$CuO${}_4$
• Zeeman driven superconductor insulator transition in strongly disordered MoC film. STM and transport studies in transverse magnetic field

Cited by in corpus (4)

• Physical properties of amorphous molybdenum silicide films for single photon detectors
• Quantum phase transition in two-dimensional NbN superconducting thin films
• Charge excitations across a superconductor-insulator transition
• Quantum Griffiths singularity in three-dimensional MoTiN superconducting films