Proximity effect of a ferromagnetic insulator in contact with a superconductor
We propose a model for conventional superconductors in contact with a ferromagnetic (or polarized paramagnetic) insulator. The model is defined by a boundary condition on the quasiclassical Green's function for the superconductor at the interface between the metal and insulating magnet. The specific boundary condition we use describes the interaction of the electrons, which tunnel into the insulating barrier, with the average exchange field of the local moments. Solutions to the quasiclassical equations and boundary condition are obtained for thin superconducting films. We obtain results for pair-breaking effects of a magnetic boundary on the transition temperature and gap of thin superconducting films. Of particular interest is the Zeeman effect in the quasiparticle density of states (DOS), which exhibits a splitting of the form 2..mu../sub e/(H+B/sup */) in an external field H. The excess splitting B/sup */ is interpreted here as an internal field in the superconductor resulting from quasiparticle tunneling into the magnetic insulator, and subsequent reflection into the superconducting film. We compare our model of the tunneling DOS with the recent measurements by Tedrow et al. on EuO/Al/Al/sub 2/O/sub 3/ tunnel junctions.
- Research Organization:
- Joseph Henry Laboratories of Physics, Jadwin Hall, Princeton University, Princeton, New Jersey 08544
- OSTI ID:
- 6719133
- Journal Information:
- Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 38:13; ISSN PRBMD
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ELECTRIC CONDUCTIVITY
ELECTRICAL EQUIPMENT
ELECTRICAL INSULATORS
ELECTRICAL PROPERTIES
EQUIPMENT
INTERACTIONS
INTERFACES
MAGNETISM
PHYSICAL PROPERTIES
PROXIMITY EFFECT
STRUCTURAL MODELS
SUPERCONDUCTIVITY
TUNNEL EFFECT