Ferromagnetika

Ferromagnetika is a term used to describe materials that exhibit ferromagnetism. Ferromagnetism is a form of magnetism that occurs only in certain materials, such as iron, nickel, and cobalt. These materials are strongly attracted by magnets and can be magnetized themselves. The defining characteristic of ferromagnetism is the existence of spontaneous magnetization, meaning that even in the absence of an external magnetic field, the material has a net magnetic moment.

This spontaneous magnetization arises from the alignment of magnetic moments of individual atoms within the material. These atomic magnetic moments are due to the intrinsic magnetic property of electrons, known as spin. In ferromagnetic materials, there are strong interactions between neighboring atomic spins, called exchange interactions, which cause them to align parallel to each other. This alignment occurs over large regions called magnetic domains. Within each domain, the magnetization is uniform, but the domains themselves may be oriented randomly in an unmagnetized material, resulting in no net macroscopic magnetization.

When an external magnetic field is applied, the domains favorably aligned with the field grow at the expense of others, and the magnetization direction within the domains can also rotate to align with the field. This process leads to a strong and often permanent magnetization of the material. Ferromagnetic materials are crucial for many technologies, including electric motors, generators, transformers, data storage devices like hard drives, and magnetic sensors. Their ability to retain magnetization makes them ideal for permanent magnets. The strength of ferromagnetism is typically measured by the saturation magnetization, which is the maximum magnetization a material can achieve.