Quantum criticality at the superconductor insulator transition probed by the Nernst effect

Abstract

The superconductor-insulator transition (SIT) is an excellent example for a quantum phase transition at zero temperature, dominated by quantum fluctuations. These are expected to be very prominent close to the quantum critical point. So far most of the experimental study of the SIT has concentrated on transport properties and tunneling experiments which provide indirect information on criticality close to the transition. Here we present an experiment uniquely designed to study the evolution of quantum fluctuations through the quantum critical point. We utilize the Nernst effect, which has been shown to be effective in probing superconducting fluctuation. We measure the Nernst coefficient in amorphous indium oxide films tuned through the SIT and find a large signal on both the superconducting and the insulating sides which peaks close to the critical point. The transverse Peltier coefficient, ${\alpha }_{xy}$ which is the thermodynamic quantity extracted from these measurements, follows quantum critical scaling with critical exponents $\nu \sim 0.7$ and $z\sim 1$ which is consistent with a clean XY model in 2+1 dimensions.

6 pages, 3 figures

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Cited by in corpus (11)

• Unconventional Superconducting Quantum Criticality in Monolayer WTe2
• AC Measurement of the Nernst effect of thin films at low temperatures
• Charge excitations across a superconductor-insulator transition
• Enhancement of Superconductivity upon reduction of carrier density in proximitized graphene
• Universal Voltage Fluctuations in Disordered Superconductors
• Nernst effect and its thickness dependence in superconducting NbN films
• Study on fluctuations of interface-enhanced superconductivity in ultrathin FeSe/SrTiO3 by the Nernst effect
• Nernst Sign-Reversal in the Hexatic Vortex Phase of Weakly Disordered a-MoGe Thin Films
• Spin-Polarized Tunneling in Critically Disordered Be-Al Bilayers
• Superconducting Dirac point in proximetized graphene
• Proximitized insulators from disordered superconductors