remanenten

Remanent magnetization, commonly referred to as remanence, is the residual magnetization that a ferromagnetic material retains after an external magnetizing field is removed. It results from the partial alignment of magnetic domains that persists due to energy barriers between domain configurations. The remanence is quantified by remanent magnetization Mr (A/m) or by remanent flux density Br (T), defined as the magnetization or magnetic flux density at zero applied field on a hysteresis loop.

In a standard magnetization process, increasing the field saturates the material; when the field is reduced to zero, some magnetization remains. The ratio of Br to the saturation flux density Bs gives a sense of loop squareness. The presence of remanence is critical for permanent magnets, where a high remanence helps maintain a magnetic field without power input.

Materials are classified as hard or soft magnets depending on their coercivity. Hard magnets (high coercivity) retain remanence well and are used in motors, generators, and magnetic assemblies. Soft magnets (low coercivity) have small remanence when the field is removed and are used where high permeability and fast response are needed.

Temperature and aging affect remanence. As temperature approaches the Curie point, magnetic ordering diminishes, reducing remanence. Mechanical stress and demagnetizing fields can also reduce it over time. Measuring remanence is commonly done with magnetometers such as a vibrating-sample magnetometer or a B-H loop trace. Understanding remanence is essential in designing magnetic storage, permanent magnets, and electromagnetic devices.