Energy gap of ferromagnet-superconductor bilayers

Klaus Halterman, Oriol T. Valls

Research output: Contribution to journalArticlepeer-review

7 Scopus citations

Abstract

The excitation spectrum of clean ferromagnet-superconductor bilayers is calculated within the framework of the self-consistent Bogoliubov-de Gennes theory. Because of the proximity effect, the superconductor induces a gap in the ferromagnet spectrum, for thin ferromagnetic layers. The effect depends strongly on the exchange field in the ferromagnet. We find that as the thickness of the ferromagnetic layer increases, the gap disappears, and that its destruction arises from those quasiparticle excitations with wave vectors mainly along the interface. We discuss the influence that the interface quality and Fermi energy mismatch between the ferromagnet and superconductor have on the calculated energy gap. We also evaluate the density of states in the ferromagnet, and we find it in all cases consistent with the gap results.

Original languageEnglish (US)
Pages (from-to)151-158
Number of pages8
JournalPhysica C: Superconductivity and its applications
Volume397
Issue number3-4
DOIs
StatePublished - Oct 15 2003

Keywords

  • Bilayers
  • Energy gap
  • Proximity effect
  • Superconductivity

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