Magnetic semiconductors and half-metals

Variants of fully spin-polarized electronic structures that may be found in ferromagnetic metals, semimetals and semiconductors are reviewed, with examples. A simple classification scheme is presented, with six broad categories. The attribution of a material to a particular category is based on chemical systematics, or density functional theory calculations. A simplified notation for the electronic structure of these ferromagnets is proposed. (Some figures in this article are in colour only in the electronic version)