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arXiv · 1706.02898

The influence of the in-plane lattice constant on the superconducting transition temperature of FeSe0.7Te0.3 thin films

Feifei Yuan·Kazumasa Iida·Vadim Grinenko·Paul Chekhonin·Aurimas Pukenas·Werner Skrotzki·Masahito Sakoda·Michio Naito·Alberto Sala·Marina Putti·Aichi Yamashita·Yoshihiko Takano·Zhixiang Shi·Kornelius Nielsch·Ruben Huehne
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Abstract

Epitaxial Fe(Se,Te) thin films were prepared by pulsed laser deposition on (La0.18Sr0.82)(Al0.59Ta0.41)O3 (LSAT), CaF2-buffered LSAT and bare CaF2 substrates, which exhibit an almost identical in-plane lattice parameter. The composition of all Fe(Se,Te) films were determined to be FeSe0.7Te0.3 by energy dispersive X-ray spectroscopy, irrespective of the substrate. Albeit the lattice parameters of all templates have comparable values, the in-plane lattice parameter of the FeSe0.7Te0.3 films varies significantly. We found that the superconducting transition temperature (Tc) of FeSe0.7Te0.3 thin films is strongly correlated with their a-axis lattice parameter. The highest Tc of over 19 K was observed for the film on bare CaF2 substrate, which is related to unexpectedly large in-plane compressive strain originating mostly from the thermal expansion mismatch between the FeSe0.7Te0.3 film and the substrate.

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Feifei Yuan, Kazumasa Iida, Vadim Grinenko, Paul Chekhonin, Aurimas Pukenas, Werner Skrotzki, Masahito Sakoda, Michio Naito, Alberto Sala, Marina Putti, Aichi Yamashita, Yoshihiko Takano, Zhixiang Shi, Kornelius Nielsch, Ruben Huehne. 2017-06-09. The influence of the in-plane lattice constant on the superconducting transition temperature of FeSe0.7Te0.3 thin films. https://doi.org/10.1063/1.4989566

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