Magnetic reader testing for asymmetric oscillation noise

Abstract Properties of noise in operation bandwidth of magnetoresistive readers arising from asymmetric oscillations of magnetization have been studied experimentally using high bandwidth time domain measurements. Different reader geometries, temperatures and external fields were used to identify the main factors leading to noise of this type. We investigate correlation between noise in device operation bandwidth and instantaneous amplitude of thermally excited magnetic resonance, which has been previously shown to correspond to asymmetric oscillations of the free layer. It is also found that waveform skewness may be used as a proxy for this correlation. We propose a routine for identification and clear differentiation of noise due to asymmetric oscillations and random telegraph noise in our experimental samples. We also introduce a method to mitigate the effect and improve the signal to noise ratio.