Thermally activated magnetization fluctuations in spin valve and GMR sensors: mode theory and experimental measurements

Summary form only given. Thermal induced magnetization fluctuations in GMR sensors have recently been shown to produce measurable noise in current high density transducer designs. Because these fluctuations vary inversely with sensor volume, as the recording density is increased, this noise may dominate the system SNR and become the mechanism that limits achievable areal densities. Here, we present a new theoretical analysis that involves thermal activation of the eigenmodes of the thin film sensor. Experimental measurements of noise power spectra to about 8 GHz are also shown for a variety of spin valve heads. Comparison with theory is utilized to determine the damping constant and to show the sensitivity of this noise on transducer parameters.