Ultra-long quasiparticle relaxation times in the superconducting state of FeSe

ORAL

Abstract

We report on measurements of the in-plane microwave conductivity of FeSe in the superconducting state. Our measurements were performed from 0.5 to 20 GHz and from 1.2 to 10 K by means of bolometric broadband microwave spectroscopy. In this frequency range, we are sensitive to the charge dynamics of thermally excited quasiparticles. We observe a dramatic narrowing in the conductivity spectra below Τc, corresponding to a rapid suppression of quasiparticle scattering. Using a phenomenological model, we extract a temperature-dependent quasiparticle relaxation rate Γ from the conductivity, which can be understood as the sum of two contributions. The contribution to Γ from inelastic scattering has an exponential temperature dependence. This implies that the excitation spectrum responsible for the inelastic scattering of quasiparticles is electronic in origin and gapped below Τc. The contribution to Γ from elastic scattering is consistent with Born-limit scattering from a dilute concentration of impurities. At 1.2 K, the quasiparticle relaxation rate reaches a value corresponding to a mean free path greater than 100 μm.


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Presenters

  • Graham Baker

    Stewart Blusson Quantum Matter Institute, University of British Columbia

Authors

  • Graham Baker

    Stewart Blusson Quantum Matter Institute, University of British Columbia

  • James Day

    Stewart Blusson Quantum Matter Institute, University of British Columbia

  • Shun Chi

    University of British Columbia, Quantum Matter Institute, University of British Columbia, Univ of British Columbia

  • Ryan P Day

    University of British Colombia, QMI, University of British Columbia, Physics and Astronomy, University of British Columbia, Quantum Matter Institute, University of British Columbia, University of British Columbia, Department of Physics & Astronomy, University of British Columbia

  • Ruixing Liang

    Stuart Blussom Quantum Matter Institute, University of British Columbia, University of British Columbia, Univ of British Columbia

  • Walter Hardy

    University of British Columbia, Quantum Matter Institute, University of British Columbia

  • Douglas Bonn

    Stewart Blusson Quantum Matter Institute, University of British Columbia, Stewart Blusson Quantum Matter Institute, University of British Columbia, Quantum Matter Institute, University of British Columbia