9561823 Daughton This Small Business Innovation Research (SBIR) Phase I project will investigate how narrow width (0.1-0.3 micron) stripes of Giant Magnetoresistance multilayers can form new magnetic structures, which look promising for magnetic field sensors and for tape and disk read heads. Initial data on these narrow stripes show two magnetic states, each of which gives linear changes in stripe resistance with applied magnetic fields, but with opposite polarities. This magnetic structure results from a number of magnetic characteristics, including bilinear and biquadratic exchange between magnetic layers, exchange coupling within magnetic layers, magnetostatic energy, and crystalline and field-induced anisotropies. The magnetic configuration improves sensitivity by compensating anti-ferromagnetic coupling with size effects in the nanometer scale stripes, and improves noise characteristics by utilizing single domain devices. In Phase I a computer model will be developed to predict the magnetoresistance behavior of the stripes as a function of line width and material parameters. A hybrid sensor assembly will be fabricated and characterized using these narrow stripes, and a read head will be designed for very narrow track widths. In Phase II a monolithic sensor and a narrow track read head will be demonstrated. Commercial applications include high sensitivity magnetic field sensors for medical, industrial, and automotive sectors and read heads for very high density disk and tape drives.
