Quantum criticality at the superconductor to insulator transition revealed by specific heat measurements

Abstract

The superconductor-insulator transition (SIT) is considered an excellent example of a quantum phase transition which is driven by quantum fluctuations at zero temperature. The quantum critical point is characterized by a diverging correlation length and a vanishing energy scale. Low energy fluctuations near quantum criticality may be experimentally detected by specific heat, $c_{\mathrm{p}}$, measurements. Here, we use a unique highly sensitive experiment to measure $c_{\mathrm{p}}$ of two-dimensional granular Pb films through the SIT. The specific heat shows the usual jump at the mean field superconducting transition temperature $T_{\mathrm{c}}^{\mathrm{mf}}$ marking the onset of Cooper pairs formation. As the film thickness is tuned toward the SIT, $T_{\mathrm{c}}^{\mathrm{mf}}$ is relatively unchanged, while the magnitude of the jump and low temperature specific heat increase significantly. This behaviour is taken as the thermodynamic fingerprint of quantum criticality in the vicinity of a quantum phase transition.

9 pages, 5 figures, 1 table

References in corpus (8)

• Fermi-liquid instabilities at magnetic quantum phase transitions
• Quantum Criticality in Heavy Fermion Metals
• 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
• Quantum Metallicity on the High-Field Side of the Superconductor-Insulator Transition
• Attojoule calorimetry of mesoscopic superconducting loops

Cited by in corpus (10)

• Niobium nitride thin films for very low temperature resistive thermometry
• Quantum criticality at the superconductor insulator transition probed by the Nernst effect
• Crossover from impurity-controlled to granular superconductivity in (TMTSF)2ClO4
• Quantum thermodynamics of nanoscale thermoelectrics and electronic devices
• Specific Heat Signature of the Berezinskii-Kosterlitz-Thouless Transition in Ultrathin Superconducting Films
• Tunneling probe of fluctuating superconductivity in disordered thin films
• Specific Heat of Thin Phonon Cavities at Low Temperature: Very High Values Revealed by ZeptoJoule Calorimetry
• Topological Description of the Solidification of Undercooled Fluids and the Temperature Dependence of the Thermal Conductivity of Crystalline and Glassy Solids Above Approximately 50 K
• Local spectroscopies across the superconductor-insulator transition
• Proximitized insulators from disordered superconductors