Conductance modulation by spin precession in noncollinear ferromagnet normal-metal ferromagnet systems

We study diffusive transport through ferromagnet normal-metal ferromagnet s ystems, with arbitrary but fixed magnetization directions of the ferromagne tic reservoirs and orientations of a magnetic field applied to the normal m etal. For noncollinear configurations, the complex mixing conductance G(dag ger 1) describes the transport of spins noncollinear to the magnetizations of the ferromagnetic reservoirs. When ImG(dagger 1)not equal 0, the total c onductance of the system in the presence of a magnetic field can be asymmet ric with respect to time reversal. The total conductance changes nonmonoton ically with the magnetic held strength for different magnetic configuration s. This modulation of the conductance is due to the precession of the spin accumulation in the normal metal. The difference between the conductance of the parallel and antiparallel configurations can be either positive or neg ative as a function of the applied magnetic held. This effect should be bes t observable on Al single crystals attached to ferromagnetic electrodes by means of tunnel junctions or metallic contacts.