Ferrimagnetic Material

any of the materials in which the magnetic moments of ions are ferrimagnetically ordered at temperatures below the Curie point. Most ferrimagnetic materials are ionic crystals containing magnetic ions of various elements or of a single element. The ions either have different valences or else occupy different crystallographic sites.

Of the ferrimagnetic materials that have been thoroughly studied, ferrites constitute the broadest class. Hexagonal ternary fluorides (RbNiF₃, CsNiF₃, TlNiF₃, CsFeF₃) make up an important group of ferrimagnetic crystals; these substances are of particular interest because of their transparency in the optical region of the spectrum. Ferrimagnetic materials also include a number of alloys and intermetallic compounds. In most cases, these materials contain atoms of the rare-earth elements. Of particular interest are compounds of the type RMe₅, where R denotes a rare-earth ion and Me is an ion of the iron triad; an example is provided by GdCo₅.

Ferrimagnetic materials are used in radio engineering as cores for high-frequency circuits and in microwave engineering as non-reciprocal components. They serve as memory components in computers, and they are also used in making permanent magnets.