Specific Heat Measurements through the Superconductor-Insulator Quantum Phase Transition

Orateur : Aviad FRYDMAN (Bar Ilan University)

The superconductor-insulator transition (SIT) is a prototype of a quantum phase transition which is very versatile experimentally : varying a non-thermal tuning parameter such as disorder, thickness, composition, magnetic field or gate-voltage causes the system to switch from a superconductor to an insulator. Though there has been increasing interest in this topic, the SIT has never been addressed from a thermodynamic point of view. So far the experimental study of the SIT has mainly concentrated on dc resistivity based measurements such as transport and magnetoresistance and on global and local tunneling spectroscopy. In my talk I will describe an experiment designed to go beyond conventional transport measurement. We use a unique highly sensitive setup to measure the specific heat of ultrathin Pb films through the SIT. The evolution of the specific heat through the quantum critical point in both granular and continuous films shows signatures for quantum criticality at the SIT and provides important information on electronic phenomena in the vicinity of the quantum phase transition.

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