Jälkimagnetoitumisena

Jälkimagnetoitumisena, also known as remanence or residual magnetism, refers to the weak magnetic field that remains in a ferromagnetic material after the external magnetizing field has been removed. This phenomenon is a key characteristic of ferromagnetic substances and is a fundamental aspect of how they retain their magnetization. When a ferromagnetic material is exposed to a strong magnetic field, its magnetic domains align in the direction of the applied field. Upon removal of this external field, not all of these domains revert to their original random orientation. A portion of this alignment persists, resulting in a net magnetic moment within the material.

The strength of the jälkimagnetoitumisena depends on several factors, including the material's composition, its magnetic history (how it was magnetized), and the strength of the original magnetizing field. Materials with high coercivity generally exhibit a stronger remanence, meaning they retain their magnetism more effectively. This property is crucial for applications such as magnetic storage devices, like hard drives and magnetic tapes, where information is encoded by magnetizing small areas of the material. Permanent magnets also rely on jälkimagnetoitumisena to maintain their magnetic strength over time. Understanding and controlling residual magnetism is therefore essential in various technological fields.