Spin-dependent thermoelectric phenomena in 3D interconnected nanowire networks

This Master thesis investigates the spin-dependent thermoelectric properties of three-dimensional interconnected nanowire networks made of nickel-iron (Ni-Fe) alloys. Homogeneous and multilayered nanowires have been studied. Track-etched polymer membrane were used as template, allowing the filling of the crossed nanopores by electrodeposition from a single electrolyte bath. The connectivity between the nanowires allows the system to be self-supported and mechanically stable after the polymer template dissolution. Moreover, transport and magnetotransport measurements are easily performed in current-perpendicular- to-plane (CPP) configuration. High values of giant magnetoresistance (GMR) of 20% at room temperature and 60% at 15 K for multilayered permalloy/copper (Py/Cu) crossed nanowires were measured, comparable with the values obtained on arrays of parallel nanowires. Furthermore, spin-dependent Seebeck coefficients have been determined based on magneto-Seebeck measurements on multilayered Py/Cu crossed nanowires, leading to a difference Sup − Sdown of −12 μV/K. Finally, the control of the Ni-Fe alloy composition allows to measure Seebeck coefficients up to −46 μV/K.