Manipulating NiFe/AlOx interfacial chemistry for the spin-polarized electrons transport

Through vacuum annealing, interfacial chemical composition of sputter-deposited AlOx/NiFe/AlOx can be controlled for electron transport manipulation. Chemical status change at the NiFe/AlOx interface was quantified by X-ray photoelectron spectroscopy and correlated to the structure and electron transport properties of the heterostructure. It is found that elemental Al existed in the insulting AlOx after annealing at intermediate temperature can improve the AlOx/NiFe interface and thus favor the electronic transport. Annealing at higher temperature will result in native AlOx formation and degrade transport properties due to the NiFe/AlOx interfaces deterioration caused by significant difference in thermal expansion coefficients of the two materials.