Materials Research Express (Jan 2020)

Inhomogeneous superconductivity in thin crystals of FeSe1−xTex (x = 1.0, 0.95, and 0.9)

  • Ritsuko Eguchi,
  • Megumi Senda,
  • Eri Uesugi,
  • Hidenori Goto,
  • Akihiko Fujiwara,
  • Yasuhiko Imai,
  • Shigeru Kimura,
  • Takashi Noji,
  • Yoji Koike,
  • Yoshihiro Kubozono

DOI
https://doi.org/10.1088/2053-1591/ab7c85
Journal volume & issue
Vol. 7, no. 3
p. 036001

Abstract

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We investigated the temperature dependence of resistivity in thin crystals of FeSe _1−x Te _x (x = 1.0, 0.95, and 0.9), though bulk crystals with 1.0 ≧ × ≧ 0.9 are known to be non-superconducting. With decreasing thickness of the crystals, the resistivity of x = 0.95 and 0.9 decreases and reaches zero at a low temperature, which indicates a clear superconducting transition. The anomaly of resistivity related to the structural and magnetic transitions completely disappears in 55- to 155-nm-thick crystals of x = 0.9, resulting in metallic behavior in the normal state. Microbeam x-ray diffraction measurements were performed on bulk single crystals and thin crystals of FeSe _1−x Te _x . A significant difference of the lattice constant, c , was observed in FeSe _1−x Te _x , which varied with differing Te content (x), and even in crystals with the same x, which was mainly caused by inhomogeneity of the Se/Te distribution. It has been found that the characteristic temperatures causing the structural and magnetic transition ( T _t ), the superconducting transition ( T _c ), and the zero resistivity ( T _c ^zero ) are closely related to the value of c in thin crystals of FeSe _1−x Te _x .

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