Koerzivität

Koerzivität, also known as coercivity, is a term used in magnetism to describe a material's resistance to demagnetization. It is a fundamental property of ferromagnetic materials and is particularly important in the design and application of permanent magnets and magnetic storage media. When a magnetic material is subjected to an external magnetic field, it becomes magnetized. If this external field is then removed or reversed, the material will retain some or all of its magnetization. Koerzivität quantifies the strength of the reversed magnetic field required to completely demagnetize the material, bringing its net magnetization back to zero.

There are two common measures of koerzivität: coercivity of remanence (Hcr) and intrinsic coercivity (Hci). Hcr is the reverse magnetic field needed to reduce the remanent magnetization to zero. Hci is the reverse magnetic field needed to reduce the magnetic flux density to zero. Materials with high koerzivität are considered magnetically hard and are suitable for permanent magnets because they retain their magnetism strongly. Conversely, materials with low koerzivität are magnetically soft and are easily demagnetized, making them useful for applications like transformer cores where rapid changes in magnetization are required. The value of koerzivität is influenced by factors such as the material's composition, microstructure, and temperature.