AlternatingFieldDemagnetisierung

Alternating field demagnetization is a technique used to remove or reduce the remanent magnetization in a ferromagnetic material. This process involves exposing the material to a progressively decreasing alternating magnetic field. The principle behind this method is that the alternating field causes the magnetic domains within the material to continuously reorient themselves. As the amplitude of the alternating field is reduced, the domains are left in a more random orientation, resulting in a net magnetization close to zero.

The effectiveness of alternating field demagnetization depends on several factors, including the strength of the applied alternating field, the rate at which it is decreased, and the magnetic properties of the material being demagnetized. For complete demagnetization, the initial alternating field strength must be significantly greater than the coercive force of the material. The alternating field is typically applied along multiple axes to ensure a more uniform random distribution of magnetic domains. This technique is widely used in paleomagnetism to remove secondary magnetic signals from rock samples, allowing scientists to study the Earth's ancient magnetic field. It is also employed in various industrial applications where residual magnetism can be detrimental, such as in the calibration of magnetic sensors or the preparation of magnetic shielding materials.