Ferromagnetic materials exhibit jumps in magnetization in the presence of an applied magnetic field of increasing strength, a phenomenon that is commonly known as the Barkhausen effect. It results from the motion of domain wall boundaries of the material in response to a fluctuating magnetic field. The pattern of jumps gives important information about the material microstructure and the Barkhausen signal is used to characterize photo-optical devices, computer storage and recording media.

The pinning field associated with the movement of magnetic domain walls is modelled as a reversible Markov Chain. This enables us to obtain analytical expressions for the Barhausen jump size distribution, and to describe the behavior of the distribution in terms of a parameter associated with the roughness of the material.