Title: Impact of Atomic Defects in the Electronic States of FeSe(1-x)Sx Superconducting Crystals
When: Wednesday, February 8, (2023), 12:00
Place: Department of Condensed Matter Physics, Faculty of Sciences, Module 3, Seminar Room (5th Floor)
Speaker: Yanina Fasano, Instituto de Nanociencia y Nanotecnología, CNEA and CONICET, Bariloche, Argentina, Centro Atómico Bariloche and Instituto Balseiro, Bariloche, Argentina, On sabbatical leave at: Leibniz Institute for Solid State and Materials Research, Helmholtzstrasse 20, 01069 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 FeSe1-xSx 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 tunnelling microscopy (STM) 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. We further support these findings by means of DFT calculations.
- Impact of atomic defects in the electronic states of FeSe(1-x)Sx superconducting crystals, Jazmín Aragón Sánchez, María Lourdes Amigó, Cristian Horacio Belussi, María Victoria Ale Crivillero, Sergio Suárez, Julio Guimpel, Gladys Nieva, Julio Esteban Gayone and Yanina Fasano, J. Phys. Mater. 5 044008, (2022). [URL]