The ferromagnetic spin filter

The transmission of spin-polarized electrons across free standing Au/Co/Au foils has been investigated. A larger transmission probability for electrons with their spin polarization (P) over right arrow(0) parallel to the sample magnetization (M) over right arrow than for electrons with (P) over right arrow(0) antiparallel to (M) over right arrow is found. By choosing (P) over right arrow(0) perpendicular to M, the spin polarization rotates into the direction of (M) over right arrow and simultaneously also precesses around it. The precession around iii is the electron analogue to the Faraday rotation observed with polarized light. It is caused by the spin dependence of the inner potential of the ferromagnetic Co film.