Half-metal
A half-metal is any substance that acts as a conductor to electrons of one spin orientation, but as an insulator or semiconductor to those of the opposite orientation. Although all half-metals are ferromagnetic, most ferromagnets are not half-metals. Many of the known examples of half-metals are oxides, sulfides, or Heusler alloys.
In half-metals, the valence band for one spin orientation is partially filled while there is a gap in the density of states for the other spin orientation. This results in conducting behavior for only electrons in the first spin orientation. In some half-metals, the majority spin channel is the conducting one while in others the minority channel is.
Half-metals were first described in 1983, as an explanation for the electrical properties of Mn-based Heusler alloys.
Some notable half-metals are chromium oxide, magnetite, and lanthanum strontium manganite, as well as chromium arsenide. Half-metals have attracted some interest for their potential use in spintronics.
