title: Suppression of phase separation and giant enhancement of superconducting transition temperature in FeSe(1-x)Te(x) thin films.
abstract: We demonstrate the successful fabrication on CaF2 substrates of FeSe(1-x)Tex films with 0 ≤ x ≤ 1, including the region of 0.1 ≤ x ≤ 0.4, which is well known to be the "phase-separation region," via pulsed laser deposition that is a thermodynamically nonequilibrium method. In the resulting films, we observe a giant enhancement of the superconducting transition temperature, Tc, in the region of 0.1 ≤ x ≤ 0.4: The maximum value reaches 23 K, which is ∼ 1.5 times as large as the values reported for bulk samples ofFeSe(1-x)Te(x). We present a complete phase diagram of FeSe(1-x)Te(x) films. Surprisingly, a sudden suppression of Tc is observed at 0:1 < x < 0.2, whereas Tc increases with decreasing x for 0.2 ≤ x < 1. Namely, there is a clear difference between superconductivity realized in x = 0-0.1 and in x ≥ 0.2. To obtain a film of FeSe(1-x)Te(x) with high Tc, the controls of the Te content x and the in-plane lattice strain are found to be key factors.
authors: Department of Basic Science, University of Tokyo, Tokyo 153-8902, Japan imai@maeda1.c.u-tokyo.ac.jp.
authors: Yoshinori
authors: http://orcid.org/0000-0003-4677-4389
authors: Y
authors: Imai
authors: Department of Basic Science, University of Tokyo, Tokyo 153-8902, Japan.
authors: Yuichi
authors: Y
authors: Sawada
authors: Department of Basic Science, University of Tokyo, Tokyo 153-8902, Japan.
authors: Fuyuki
authors: F
authors: Nabeshima
authors: Department of Basic Science, University of Tokyo, Tokyo 153-8902, Japan.
authors: Atsutaka
authors: A
authors: Maeda
keywords: FeSe1−xTex; complete phase diagram; compressive strain; thin-film growth
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