Magnetoresistance of a planar spin valve with single-domain ferromagnetic probes

We are developing hybrid ferromagnetic(F)/nonmagnetic(N) structures to be used for spatially resolved measurements of the nonequilibrium spin distribution in a nonmagnetic metal. As a first step toward this goal, we have fabricated F/N/F samples with a planar geometry consisting of two single-domain ferromagnetic fingers crossed by a sub-micron wide nonmagnetic wire. When we apply the current from ferromagnet to ferromagnet via the nonmagnetic wire, the device is somewhat analogous to a traditional F/N/F perpendicular current (CPP) spin valve sandwich. Magneto-transport measurements on our sample made at liquid helium temperature show the typical spin valve effect with an amplitude consistent with estimates based on the two-current series-resistor model. We anticipate that further measurements of this kind will allow us to probe regimes of spin polarized transport not previously accessible