Relationship between superconductivity and nematicity in FeSe1-xTex (x=0-0.5) films studied by complex conductivity measurements

Hodaka Kurokawa, Sota Nakamura, Jiahui Zhao, Naoki Shikama, Yuki Sakishita, Yue Sun, Fuyuki Nabeshima, Yoshinori Imai, Haruhisa Kitano, Atsutaka Maeda

Research output: Contribution to journalArticlepeer-review

Abstract

We measured the complex conductivity, σ, of FeSe1-xTex (x=0-0.5) films in the superconducting state which show a drastic increase of the superconducting transition temperature Tc when the nematic order disappears. Since the magnetic penetration depth λ(>400 nm) of Fe(Se,Te) is longer than the typical thickness of the film (∼100 nm), we combined the coplanar waveguide resonator and cavity perturbation techniques to evaluate both the real and imaginary parts of σ. Films with a nematic order showed a qualitatively different temperature dependence in penetration depth and quasiparticle scattering time when compared with those without nematic order, suggesting that nematic order influences the superconducting gap structure. Conversely, the proportionality between superfluid density ns (∝λ-2) and Tc was observed irrespective of the presence or absence of nematic order. This result indicates that the amount of superfluid has a stronger impact on the Tc of Fe(Se,Te) than the presence or absence of nematic order. Combining these results with band dispersions calculated using density functional theory, we propose that the change of the Fermi surface associated with nematicity is the primary factor influencing the change of Tc and the superconducting gap structure in Fe(Se,Te).

Original languageEnglish
Article number014505
JournalPhysical Review B
Volume104
Issue number1
DOIs
Publication statusPublished - 2021 Jul 1

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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