title: Quantum criticality at the superconductor-insulator transition revealed by specific heat measurements.
abstract: The superconductor-insulator transition (SIT) is considered an excellent example of a quantum phase transition that 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, cp, measurements. Here we use a unique highly sensitive experiment to measure cpof two-dimensional granular Pb films through the SIT. The specific heat shows the usual jump at the mean field superconducting transition temperature marking the onset of Cooper pairs formation. As the film thickness is tuned towards the SIT, 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.
authors.affiliation: Department of Physics, Bar Ilan University, Ramat Gan 52900, Israel.|Institut NÉEL, CNRS, 25 avenue des Martyrs, F-38042 Grenoble, France.
authors.forename: S
authors.initials: S
authors.lastname: Poran
authors.affiliation: Institut NÉEL, CNRS, 25 avenue des Martyrs, F-38042 Grenoble, France.|Univ. Grenoble Alpes, Inst NEEL, F-38042 Grenoble, France.
authors.forename: T
authors.initials: T
authors.lastname: Nguyen-Duc
authors.affiliation: Department of Physics, Technion, 32000 Haifa, Israel.|Laboratoire de Physique Théorique de la Matière Condensée, CNRS UMR 7600, UPMC-Sorbonne Universités, 4 Place Jussieu, 75252 Paris, France.
authors.forename: A
authors.initials: A
authors.lastname: Auerbach
authors.affiliation: Laboratoire de Physique Théorique de la Matière Condensée, CNRS UMR 7600, UPMC-Sorbonne Universités, 4 Place Jussieu, 75252 Paris, France.
authors.forename: N
authors.initials: N
authors.lastname: Dupuis
authors.affiliation: Department of Physics, Bar Ilan University, Ramat Gan 52900, Israel.|Institut NÉEL, CNRS, 25 avenue des Martyrs, F-38042 Grenoble, France.|Univ. Grenoble Alpes, Inst NEEL, F-38042 Grenoble, France.
authors.forename: A
authors.initials: A
authors.lastname: Frydman
authors.affiliation: Institut NÉEL, CNRS, 25 avenue des Martyrs, F-38042 Grenoble, France.|Univ. Grenoble Alpes, Inst NEEL, F-38042 Grenoble, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Bourgeois