Controlling Tc through Band Structure and Correlation Engineering in Collapsed and Uncollapsed Phases of Iron Arsenides

Swagata Acharya, Dimitar Pashov, Francois Jamet, Mark Van Schilfgaarde, Mark Van Schilfgaarde

Research output: Contribution to journalArticlepeer-review

12 Scopus Citations


Recent observations of selective emergence (suppression) of superconductivity in the uncollapsed (collapsed) tetragonal phase of LaFe2As2 has rekindled interest in understanding what features of the band structure control the superconducting Tc. We show that the proximity of the narrow Fe-dxy state to the Fermi energy emerges as the primary factor. In the uncollapsed phase this state is at the Fermi energy, and is most strongly correlated and a source of enhanced scattering in both single and two particle channels. The resulting intense and broad low energy spin fluctuations suppress magnetic ordering and simultaneously provide glue for Cooper pair formation. In the collapsed tetragonal phase, the dxy state is driven far below the Fermi energy, which suppresses the low-energy scattering and blocks superconductivity. A similar source of broad spin excitation appears in uncollapsed and collapsed phases of CaFe2As2. This suggests controlling coherence provides a way to engineer Tc in unconventional superconductors primarily mediated through spin fluctuations.

Original languageAmerican English
Article number237001
Number of pages5
JournalPhysical Review Letters
Issue number23
StatePublished - 12 Jun 2020

Bibliographical note

Publisher Copyright:
© 2020 American Physical Society.

NREL Publication Number

  • NREL/JA-5F00-77311


  • arsenic compounds
  • band structure
  • Fermi level
  • iron
  • iron compounds
  • lanthanum compounds
  • spin fluctuations
  • technetium


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