Temperature Dependence of Noise in Giant- and Tunneling Magnetoresistive Vortex Sensors

Giant magnetoresistive (GMR) and tunneling magnetoresistive (TMR) spin valve sensors with a vortex-state free layer have been studied using resistance and noise measurements for temperatures from 50 to 400 K. A vortex-state free layer enables high saturation fields of the sensor while strongly reducing the phase noise and enabling a theoretically hysteresis-free transfer curve. The results show that the noise in both sensor types peaks at a temperature of about 200 K. Measurements in a saturated state enable a separation of electric and magnetic noise contributions and show that in contrast to TMR, both electric and magnetic noise contributions decrease with temperature for the GMR sample.