Introduction to Noise and Measurement Techniques

The major sources of noise in magnetoresistive systems will be discussed, including: thermal, shot, electronic, and magnetization noise. These noise mechanisms produce either voltage, current, or resistance fluctuations that limit the ultimate field sensitivity of magnetoresistive sensors. For high-bandwidth applications, thermal and shot noise can contribute significant integrated noise power owing to their frequency independent spectral content. For low frequency applications, resistance fluctuations present obstacles for achieving pico-Tesla per square-root sensitivity below 1 Hz.The fluctuations can be used as a probe of electrical transport and magnetization dynamics.