Strain effect on the superconductivity of FeSe_0.5Te_0.5 thin films induced by mica substrate

Iron-based superconductors have attracted much attention because of their promising prospects in both applied and fundamental research. Iron chalcogenide superconductors, which have the simplest structure, play an important role in this field. It has been shown that pressure or strain has remarkable influence on their superconducting transition temperatures (T_C) [1, 2]. To further explore the strain effect, we grow epitaxial FeSe_0.5Te_0.5 (FST) thin films on muscovite mica substrates by pulsed laser deposition, because different strains can be induced by bending mica owing to the flexibility of mica after mechanical exfoliation [3]. It is shown that T_C value of FST increases under compressive strain while decreases under tensile strain. It is also indicated that the relative orientations of electrical current and strain are important in the change of transport property. The results are discussed by considering different contributions. This work is helpful to understand superconducting mechanism of iron chalcogenide superconductors, and shows a great potential for novel applications with flexible superconductors.
[1] S. Masaki et al., J. Phys. Soc. Jpn. 78, 063704 (2009)
[2] E. Bellingeri et al., Appl. Phys. Lett. 96, 102512 (2010)
[3] Y. Chu et al., npj Quantum Mater. 2, 67 (2017)