Jälkimagnetoituminen

Jälkimagnetoituminen is a Finnish term that translates to "remanence" or "residual magnetism" in English. It refers to the magnetization that remains in a ferromagnetic material after the external magnetic field that caused the magnetization has been removed. This phenomenon is a fundamental property of magnetic materials and is crucial for the operation of many magnetic devices.

When a ferromagnetic material is exposed to a magnetic field, its magnetic domains align with the field. Even after the external field is removed, a portion of this alignment persists, creating a net magnetic moment within the material. The strength of this residual magnetism depends on the material's properties, such as its coercivity, and the history of its exposure to magnetic fields. Materials with high coercivity retain their magnetization more strongly, making them suitable for permanent magnets.

The concept of remanence is essential in understanding how magnetic storage media, like hard drives and magnetic tapes, function. The data stored on these media is represented by regions of varying magnetization, which are effectively examples of remanence. Similarly, the permanent magnets used in motors, generators, and various sensors rely on the remanent magnetization of specialized alloys. Studying jälkimagnetoituminen helps in designing and improving magnetic materials and devices for specific applications.