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Giant Grüneisen parameter in a superconducting quantum paraelectric

ORAL

Abstract

Superconductivity and ferroelectricity are typically thought of as incompatible because the former needs free carriers, but the latter is usually suppressed by free carriers. This is unless the carrier concentration is sufficiently low to allow for polar distortions and mobile electrons to cooperate. In the case of strontium titanate with low carrier concentration, superconductivity and ferroelectricity have been shown to be correlated via various tuning methods, such as strain. Here, we report theoretically and experimentally evaluated Grüneisen parameters whose divergent giant values under tensile stress indicate that the dominant phonon mode which enhances the superconducting order is the ferroelectric transverse soft phonon mode. This finding puts strong constraints on other phonon modes as the main contributors to the enhanced superconductivity in strained strontium titanate. The methodology shown here can be applied to strain-tune and probe properties of other materials with polar distortions including topologically non-trivial ones.

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Presenters

  • Ilya Sochnikov

    Physics Department, University of Connecticut, University of Connecticut

Authors

  • Jacob D Franklin

    Department of Physics, University of Connecticut, Physics Department, University of Connecticut, University of Connecticut

  • Bochao Xu

    Department of Physics, University of Connecticut, University of Connecticut, Physics Department, University of Connecticut

  • Aditi Mahabir

    Physics, University of Connecticut, University of Connecticut

  • Alexander Balatsky

    Physics, University of Connecticut, Department of Physics, University of Connecticut, Department of Physics, University of Connecticut (UCONN), University of Connecticut

  • Ulrich Aschauer

    University of Bern, Bern Switzerland

  • Ilya Sochnikov

    Physics Department, University of Connecticut, University of Connecticut