Enhancement of magnetoresistance sensitivity in a Co/Cu artificial superlattice

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Abstract
Co/Cu artificial superlattices were fabricated with an rf-magnetron sputtering system. Cu deposited on silicon substrate was used as an underlayer. The Co/Cu artificial superlattice was not only textured but also rotationally aligned to the Si substrate, which presumably rendered the Si[100] an easy axis in plane direction. A strong (100) preferred orientation was developed as the thickness of the cobalt decreased and the thickness of the copper underlayer increased. This strong preferred orientation turned out to be closely related to the reduction of the saturation field as well as the value of the magnetoresistance. By addition of 6 at. % nickel to the copper underlayer, electrical shunting through the thick underlayer could be effectively depressed. In [Cu(20 Å)/Co(30 Å)]20Cu-6 at. % Ni(200 Å)‖Si, an 18.5% magnetoresistance could be obtained within a ±100 Oe field range at room temperature.