Barkhausen Effect in Nickel-Iron Films

Abstract

A statistical study of Barkhausen discontinuities in nickel-iron films has been made by observing independent hysteresis loops obtained from different areas of each film. The magnetization changes were detected by photomultiplier sensing of the light output from a standard Kerr magneto-optical apparatus. Observations could thus be restricted to any desired region of the film by suitably varying the light spot size and location. The sequence of Barkhausen discontinuities in a given reversal is generally random and cannot be predicted by the sequence in a previous reversal. The statistical distribution of discontinuity sizes obtained from many reversals is shown to be well described by a simple model of wall moton in which the probability of a wall stopping in an interval of distance dx is proportional to dx. The applicability of this model to bulk materials is discussed.