Strong surface termination dependence of the electronic structure of polar superconductor LaFeAsO revealed by nano-ARPES

Sung Won Jung*, Luke C Rhodes, Matthew D Watson, Daniil V Evtushinsky, Cephise Cacho, Saicharan Aswartham, Rhea Kappenberger, Sabine Wurmehl, Bernd Büchner, Timur K Kim*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The electronic structures of the iron-based superconductors have been intensively studied by using angle-resolved photoemission spectroscopy (ARPES). A considerable amount of research has been focused on the LaFeAsO family, showing the highest transition temperatures, where previous ARPES studies have found much larger Fermi surfaces than bulk theoretical calculations would predict. The discrepancy has been attributed to the presence of termination-dependent surface states. Here, using photoemission spectroscopy with a sub-micron focused beam spot (nano-ARPES) we have successfully measured the electronic structures of both the LaO and FeAs terminations in LaFeAsO. Our data reveal very different band dispersions and core-level spectra for different surface terminations, showing that previous macro-focus ARPES measurements were incomplete. Our results give direct evidence for the surface-driven electronic structure reconstruction in LaFeAsO, including formation of the termination-dependent surface states at the Fermi level. This experimental technique, which we have shown to be very powerful when applied to this prototypical compound, can now be used to study various materials with different surface terminations.
Original languageEnglish
Article number113018
Number of pages9
JournalNew Journal of Physics
Issue number11
Early online date10 Nov 2022
Publication statusPublished - 10 Nov 2022


  • Iron-based superconductors
  • Photoemission
  • Electronic structure
  • Polar surface


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