Magnetic noise sources

An emerging focus of our research is the investigation of magnetic noise sources in ferromagnetic materials subjected to a magnetizing-demagnetizing field. We have recently initiated experimental work aimed at characterizing Barkhausen noise.

In 1919, the German physicist Heinrich Barkhausen discovered that during a continuous (i.e., slowly varying) process of magnetization or demagnetization, the magnetization of a material changes in a series of discrete, minute steps. This phenomenon provided experimental evidence supporting the domain theory of ferromagnetism, proposed in 1906 by Pierre-Ernest Weiss. When a time-dependent "driving" magnetic field is applied slowly to a ferromagnetic material, Barkhausen noise can be observed. It reaches its maximum amplitude when the driving field crosses the coercive value.