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Title: Dramatic changes in the electronic structure upon transition to the collapsed tetragonal phase in CaFe2As2

We use angle-resolved photoemission spectroscopy and density functional theory calculations to study the electronic structure of CaFe2As2 in the collapsed tetragonal (CT) phase. This unusual phase of iron arsenic high-temperature superconductors was hard to measure as it exists only under pressure. By inducing internal strain, via the postgrowth thermal treatment of single crystals, we were able to stabilize the CT phase at ambient pressure. We find significant differences in the Fermi surface topology and band dispersion data from the more common orthorhombic-antiferromagnetic or tetragonal-paramagnetic phases, consistent with electronic structure calculations. The top of the hole bands sinks below the Fermi level, which destroys the nesting present in parent phases. The absence of nesting in this phase, along with an apparent loss of Fe magnetic moment, are now clearly experimentally correlated with the lack of superconductivity in this phase.
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  1. Ames Lab., Ames, IA (United States)
  2. Goethe Univ., Frankfurt (Germany)
Publication Date:
OSTI Identifier:
Report Number(s):
IS--J 8266
Journal ID: ISSN 2469-9950
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review B; Journal Volume: 89; Journal Issue: 02
American Physical Society (APS)
Research Org:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States