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The effects of an NiFe/MgO interface on the thermoelectric transport behavior of spin-polarized electrons were studied by measuring the Seebeck coefficient ( S ) and anisotropic magneto-thermopower (AMT) of an MgO/NiFe/MgO multilayer structure. Thermally annealing this multilayer was found to increase S (343% at 450 °C) through crystallization of interfacial MgO, which allows conductive electrons to achieve better specular scattering at the interface. The AMT was also increased by annealing (139% at 450 °C), but this is ascribed to a chemical metallization of interfacial Fe in which the deposition-induced oxygen atoms migrate out of the NiFe layer. This helps to recover the magnetization of NiFe, thereby causing spin-dependent thermoelectric transport behavior at the interface. [ABSTRACT FROM AUTHOR]

The anisotropic magnetoresistance value (ΔR/R) and magnetic field sensitivity (Sv) of NiFe films can be remarkably enhanced by using Al2O3 encapsulation, and the Sv is comparable to that of a spin valve. For an ultrathin NiFe film with the structure of Ta/Al2O3/NiFe/Al2O3/Ta, the Al2O3 layers suppress the formation of the magnetic dead layers and the interdiffusions between the NiFe layer and Ta layers, and decrease the current shunting of the Ta layers. More importantly, the flatter Al2O3/NiFe and NiFe/Al2O3 interfaces can significantly enhance the specular reflection of conduction electrons and lead to a higher ΔR/R. In addition, the formations of the NiFe (111) texture and the columnar grains by annealing can also increase the ΔR/R. [ABSTRACT FROM AUTHOR]