Proximity effect between superconductors and ferromagnets

Superconductors (S) can be employed to probe the spin polarization of ferromagnetic metals (F) by virtue of Andreev reflection. Using nanocontacts defined by e-beam lithography, the spin-polarization of the current across an S/F interface can be determined reliably. Via non-local Andreev reflection, an incident electron from a nanocontact is retroreflected as a hole in an adjacent contact, forming spatially separated but entangled Einstein–Podolski–Rosen pairs. Finally, the proximity-induced superconductivity can be probed by magnetization measurements.