Wan Hang Fong,1 Archie B. Morfoot,1, 2 Timur K. Kim,2 Amir A. Haghighirad,3 and Amalia I. Coldea1

1 Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, UK
2 Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK
3 Karlsruhe Institute of Technology, 76021 Karlsruhe, Germany

Superconducting iron-chalcogenides FeSe1-xTex have a rich phase diagram due to the different competing electronic phases with superconductivity, such as nematic and spin-density wave phases [1]. With increasing Te concentration, x, the chalcogen pz band is shifted down towards the Fermi level [2] and hybridizes with the Fe d bands, creating band inversion and Dirac surface states [3], as a prerequisite for creating topological superconductors [4]. Here, we investigate the effects of the uniaxial strain on FeSe1-xTex in the vicinity of the nematic end point (x~0.3-0.5) using both angle-resolved photoemission spectroscopy and transport studies to explore the changes in electronic structure and superconductivity. We identify changes in the spectral weight and transition temperatures as a function of increasing strain which is applied along the orthorhombic direction. By comparing the experimental data with band-structure calculations and other related iron-chalcogenide superconductors, we assess the effects induced by strain, the role of electronic correlations and of the nematic critical fluctuations on superconductivity.

References
[1] R.M. Fernandes, et al. Nature 601, 35–44 (2022).
[2] A. Morfoot, et al. Commun Phys 6, 362 (2023).
[3] Z. Wang, et al. Physical Review B 92, 115119 (2015).
[4] P. Zhang, et al. Science 360, 182-186 (2018).