koersiivisuus

Koersiivisuus is a term that describes the property of a material to retain its magnetization after the external magnetic field is removed. It is a crucial characteristic in the study of magnetism, particularly for ferromagnetic and ferrimagnetic materials. High koersiivisyys indicates that a material is difficult to demagnetize, making it suitable for applications such as permanent magnets. Conversely, materials with low koersiivisyys are easily magnetized and demagnetized, which is desirable for applications like transformer cores and magnetic recording media where the magnetic state needs to change frequently.

The koersiivisyys is typically measured in units of magnetic field strength, often in amperes per meter (A/m) or oersteds (Oe). It is determined by measuring the magnetic field required to reduce the magnetization of a material to zero after it has been saturated. This value is represented as the point where the hysteresis loop of the material intersects the magnetic field axis. Factors such as the material's composition, crystal structure, grain size, and the presence of impurities can significantly influence its koersiivisyys. Understanding koersiivisyys is essential for selecting appropriate magnetic materials for specific technological uses.