  Magnetoresistive spin valve sensors based on the giant- (GMR) and tunnelling-
(TMR) magnetoresisitve effect with a flux-closed vortex state free layer design
are compared by means of sensitivity and low frequency noise. The vortex state
free layer enables high saturation fields with negligible hysteresis, making it
attractive for applications with a high dynamic range. The measured GMR devices
comprise lower pink noise and better linearity in resistance but are less
sensitive to external magnetic fields than TMR sensors. The results show a
comparable detectivity at low frequencies and a better performance of the TMR
minimum detectable field at frequencies in the white noise limit.
