Energy gap of ferromagnet-superconductor bilayers

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 wavevectors 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.

arXiv comment13 pages including 5 figures

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• Induced Energy Gap in Finite-Sized Superconductor/Ferromagnet Hybrids
• Tunneling conductance in Superconductor/Ferromagnet junctions: a self consistent approach
• Characteristic energies, transition temperatures, and switching effects in clean SNS graphene nanostructures
• Supergap and subgap enhanced currents in asymmetric {S_1FS_2} Josephson junctions
• Local Density of States and Order Parameter Configurations in Layered Ferromagnet-Superconductor Structures
• Electron-hole coherence in core-shell nanowires with partial proximity induced superconductivity