Local atomic structure of superconducting FeSe1−xTex

Abstract

The isovalent substitution of Te for Se in the superconducting α-FeSe raises TC where the average chalcogen–Fe bond angle decreases and the chalcogen-Fe distance increases. Locally, however, the Se and Te ions do not share the same site and have two distinct z coordinates, in contrast to what is presumed in the P4/nmm symmetry. The local bond angle between the chalcogens and Fe increases with the substitution, consistent with the rise in TC, the Fe–Te bonds become shorter than in the binary FeTe, while the Fe–Se bonds stay the same as in the binary. Ab initio calculations based on spin density functional theory yielded an optimized structure with distinct z coordinates for Se and Te, in addition to a stronger hybridization of Te with Fe.

Source-reported materials — not catalogue approval

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