Thermal Spin-Valve Effect in Magnetic Multi-layered Nanowires

We have investigated the influence of the spin-dependent scattering on the heat transports in NiFe/Cu/NiFe and Co/Cu/Co tri-layered nanowires. The thermal conductivity and its spin dependence for the tri-layered wires have been evaluated by using an integrated nano-sized thermo couple. We find that the thermal spin-valve effect is always approximately 8 times larger than the electrical spin-valve effect, namely giant magnetoresistance effect. The numerical simulation with the experimental results enable us to estimate the thermal conductivity for the tri-layered wire and its spin dependence. Surprisingly, the spin dependence of the thermal conductivity for the Co/Cu/Co wire is as high as 8%, which is much larger than the electrical one. This indicates a high potential application of the thermal spin-valve effect.