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TT: Fachverband Tiefe Temperaturen

TT 54: Fe-based Superconductors

TT 54.10: Vortrag

Donnerstag, 19. März 2020, 12:00–12:15, HSZ 201

One-Electron-Pocket Model of FeSe: Quasiparticle Interference — •Matthias Eschrig^1,2, Luke C. Rhodes^2,3,4, Matthew D. Watson⁴, and Timur K. Kim⁴ — ¹Universität Greifswald, Germany — ²Royal Holloway, University of London, UK — ³University of St. Andrews, UK — ⁴Diamond Light Source, Harwell Campus, UK

The one-electron-pocket model of FeSe was introduced to account for experimental observations in angle-resoved photoemission (ARPES) experiments. Quasiparticle interference (QPI) measurements of FeSe, obtained via scanning tunneling microscopy, have previously been interpreted as being consistent with a theoretical model where the Fermi surface consists of one hole pocket and two electron pockets and exhibits a large difference in the quasiparticle weight of the d_xz and d_xy orbitals. On the contrary, orbital sensitive measurements from ARPES have been interpreted as being consistent with a model with roughly equivalent quasiparticle weights for the d_xz and d_yz orbitals, but with only one hole pocket and one electron pocket at the Fermi surface present. Here, we show that the second, one-electron-pocket, model also explains QPI experiments. We find, that it is important to apply a selection rule for QPI, that only electronic states with vanishing component of the Fermi velocity perpendicular to the scanning surface contribute to the interference pattern. By using a three-dimensional tight-binding model of FeSe, fit to ARPES measurements, we directly reproduce the experimental QPI results, within a T-matrix formalism. This unifying result for QPI and ARPES on FeSe also highlights the importance of selection rules for QPI experiments via STM.