Barkhausen

Barkhausen refers to Heinrich Barkhausen, a German physicist who is credited with discovering the Barkhausen effect in 1919. The effect arises in ferromagnetic materials when the magnetization changes in a series of abrupt jumps rather than smoothly as an external magnetic field is varied.

These jumps are due to the motion of magnetic domain walls becoming temporarily pinned by defects, grain boundaries, and other inhomogeneities in the material. As the applied field changes, domain walls accumulate stress and then release it in sudden avalanches, producing discrete changes in magnetization. The resulting signal, often called Barkhausen noise, can be detected with pickup coils and sensitive electronics.

The Barkhausen effect provided important empirical support for the domain theory of magnetism, demonstrating that magnetic domains and domain-wall motion play a central role in how magnetization changes. It also offered a practical means of probing the microstructure and mechanical state of ferromagnetic materials.

In applied science and engineering, Barkhausen measurements are used for nondestructive evaluation and materials characterization. They help estimate properties such as grain size, hardness, residual stress, and heat-treatment history. The technique is valued for its sensitivity to microstructural changes and its capacity to monitor manufacturing processes and service-related material degradation.

Beyond this, the term Barkhausen may appear in other contexts as a surname, but in physics it is most closely associated with the Barkhausen effect and its accompanying noise phenomenon.