The high magnetoresistance available in magnetic tunnel junctions makes them well suited to highly sensitive magnetic field sensors. However, the low-frequency sensitivity is limited by the presence of a relatively large 1/f noise. The dominant source of noise observed in these sensors is resistance fluctuations in the tunnel barrier rather than magnetic fluctuations found in giant magnetoresistance (GMR) devices. The noise level is highly variable even among nominally identical devices, but the noise does follow trends in relation to device magnetoresistance and device size. A filtering technique used to reduce the influence of this 1/f noise is demonstrated.
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