Local spectroscopies across the superconductor-insulator transition

Abstract

We explore the manifestation of quantum fluctuations across the superconductor-insulator transition (SIT) in three different local measurements: the two-particle density of states $P(\mathbf{r},\omega )$, compressibility $\kappa (\mathbf{r})$, and diamagnetic susceptibility $\chi (\mathbf{r})$. We perform Monte Carlo simulations on the 2D quantum Josephson junction array model and present local maps of these quantities as the system is tuned across the SIT. $P(\mathbf{r},\omega )$, obtained using Maximum Entropy analytic continuation techniques, shows strongly diminished zero-energy spectral weight in nearly-insulating islands, that also correlate with regions of suppressed $\kappa (\mathbf{r})$. We investigate the signatures of quantum fluctuations in the evolution of $\kappa (\mathbf{r})$ and $\chi (\mathbf{r})$ across the SIT, distinct from thermal fluctuations. We discuss the experimental implications of our results for scanning Josephson spectroscopy, compressibility, and scanning SQUID measurements.

11 pages, 7 figures; added reference

References in corpus (5)

• Observation of Majorana Fermions in Ferromagnetic Atomic Chains on a Superconductor
• Localization of preformed Cooper-pairs in disordered superconductors
• Disorder-Induced Inhomogeneities of the Superconducting State Close to the Superconductor-Insulator Transition
• Phase fluctuations in a strongly disordered s-wave superconductor close to the metal-insulator transition
• The Higgs Mode in Disordered Superconductors Close to a Quantum Phase Transition