Effect of Carrier Differences on Magnetoresistance in Organic and Inorganic Spin Valves

Magnetoresistance in the structure of ferromagnetic/nonmagnetic/ferromagnetic spin valves are studied theoretically from the spin diffusion theory and Ohm's law. The nonmagnetic layer could be an organic or inorganic semiconductor. Carrier mobility and the spin-flip time in organic semiconductors are different from those in inorganic semiconductors, and effects of these differences on the magnetoresistance in organic and inorganic spin valves are discussed. From the calculation, it is found that the magnetoresistance in inorganic spin valves is higher than that in organic spin valves. Effects of the conductivity matching and spin-dependent interfacial resistances between ferromagnetic and nonmagnetic layers, thickness of the nonmagnetic layer, and the bulk spin polarization of the ferromagnetic layer on the magnetoresistance are also discussed.