Giant magnetroresistance properties of specular spin valve films in a current perpendicular to plane structure

Conventional and specular spin valve films in a current perpendicular to pl ane (CPP) structure have been investigated. The specular spin valve film wi th bottom type structure had two oxidized layers: one in the pinned layer, which was oxidized during an in situ deposition process, and the other in t he free layer, which was a naturally oxidized Cu/Ta cap. Both films had inc reasing resistance, R, and resistance change, DeltaR, with decreasing eleme nt size. The conventional spin valve film showed a resistance times area pr oduct, RA, of 144 m Ohm mum(2) and a resistance change area product, Delta RA, of 0.7 m Ohm mum(2) while the specular spin valve film showed RA of 112 0 m Ohm mum(2) and Delta RA of 23 m Ohm mum(2). The Delta RA of the specula r spin valve film was about 33 times larger than that of the conventional s pin valve film. The calculated magnetoresistance (MR) ratios, MRSV, of each spin valve film were 1.9% and 2.3%, respectively. We think oxidized layers in the spin valve film caused the specular electron scattering and this le ngthened the path of the conduction electrons, enhancing the interfacial an d bulk spin dependent scattering. We estimated the output voltage change of the 0.01 mum(2) element, the size required for 150 Gb/in.(2) recording den sity, of the specular spin valve film in CPP mode to be 5.3 mV. It was almo st six times larger than that of the conventional spin valve film at consta nt power consumption. Specular spin valve film are advantageous for the CPP structure element for future giant MR sensors. (C) 2001 American Institute of Physics.