Control of structural transition in FeSe_1-xTe_x thin films by changing substrate materials.

ABSTRACT: Iron chalcogenide superconductors FeSe_1-xTe_x are important materials for investigating the relation be-tween the superconductivity and the orbital and/or electronic nematic order, because the end member material FeSe exhibits a structural transition without a magnetic phase transition. However, the phase separation occurs in the region of 0.1???x???0.4 for bulk samples, and it prevents the complete understanding of this system. Here, we report the successful fabrication of epitaxial thin films of FeSe_1-xTe_x with 0???x???0.7, which includes the phase-separation region, on LaAlO₃ substrates via pulsed laser deposition. In the temperature dependences of differential resistivity for these films with 0???x???0.3, the dip- or peak- anomalies, which are well-known to be originated from the structural transition in FeSebulk samples, are observed at the characteristic temperatures, T*. The doping-temperature (x-T) phase diagram of FeSe_1-xTe_x films clearly shows that T* decreases with increasing x, and that T_c suddenly changes at a certain Te content where T* disappears, which turns out to be commonly observed for both films on LaAlO₃ and CaF₂. These indicate the importance of controlling the structural transition to achieve high T_c in iron chalcogenides.

SUBMITTER: Imai Y 

PROVIDER: S-EPMC5399356 | biostudies-literature | 2017 Apr

REPOSITORIES: biostudies-literature