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TT: Fachverband Tiefe Temperaturen

TT 34: Fe-based Superconductors

TT 34.7: Talk

Wednesday, March 29, 2023, 13:00–13:15, HSZ 103

Impact of atomic defects in the electronic states of FeSe_1−xS_x superconducting crystals — •Yanina Fasano^1,2, Jazmin Aragon Sanchez¹, Maria Lourdes Amigo¹, Esteban Gayone¹, and Gladys Nieva¹ — ¹Instituto Balseiro and Centro Atomico Bariloche, UnCuyo-CNEA, Argentina — ²Leibniz Institute for Solid State and Materials Research, Dresden, Germany

The electronic properties of Fe-based superconductors are drastically affected by deformations on their crystal structure introduced by doping and pressure. Here we study single crystals of FeSe_1−xS_x and reveal that local crystal deformations such as atomic-scale defects impact the spectral shape of the electronic core level states of the material. By means of scanning tunneling microscopy we image S-doping induced defects as well as diluted dumbbell defects associated with Fe vacancies. We have access to the electronic structure of the samples by means of x-ray photoemission spectroscopy (XPS) and show that the spectral shape of the Se core levels can only be adequately described by considering a principal plus a minor component of the electronic states. We find this result for both pure and S-doped samples, irrespective that in the latter case the material presents extra crystal defects associated to doping with S atoms. We argue that the second component in our XPS spectra is associated with the ubiquitous dumbbell defects in FeSe that are known to entail a significant modification of the electronic clouds of surrounding atoms.