Noise power spectral density in single-strip NiFeCo-Cu GMR sensors

Noise power spectral density measurement were performed on single-strip patterned NiFeCo-Cu giant magnetoresistance (GMR) multilayers with various width ranging from 2 /spl mu/m to 20 /spl mu/m. The measurements were carried out over two frequency ranges from 0.1 Hz to 100 Hz and 10 Hz to 10 kHz. Noise spectrum was obtained for various de bias fields in the presence or of an external alternating field. Noise power spectral density measurements indicate that the noise is 1/f type. In the absence of an external alternating field the 1/f noise slope showed no field dependence in both frequency ranges. The slope of the 1/f noise is approximately 1 at close to zero bias field in all samples investigated. The 11f noise slope measured in the presence of the alternating field shows field dependent noise behavior of a value of about 1.1 in the region close to zero bias but fall off at large bias field. The 1/f noise is also analyzed using the Hooge parameter /spl alpha/.