Half-metal

A half-metal is any substance that acts as a <a href="/facts/Electrical_conductor/BSuyupLP">conductor</a> to <a href="/facts/Electron/L0KBo5cW">electrons</a> of one <a href="/facts/Spin_(physics)/4Jvp7e8P">spin</a> orientation, but as an <a href="/facts/Electrical_insulation/SfSXkrh5">insulator</a> or <a href="/facts/Semiconductor/zFf3mGTE">semiconductor</a> to those of the opposite orientation. Although all half-metals are <a href="/facts/Ferromagnetism/fH3HFnSl">ferromagnetic</a> (or <a href="/facts/Ferrimagnetism/sMcg7RYt">ferrimagnetic</a>), most ferromagnets are not half-metals. Many of the known examples of half-metals are <a href="/facts/Oxide/DXtoVe1C">oxides</a>, <a href="/facts/Sulfide/d8YMjLeu">sulfides</a>, or <a href="/facts/Heusler_alloy/12ro9MxT">Heusler alloys</a>. Types of half-metallic compounds theoretically predicted so far include some Heusler alloys, such as Co2FeSi, NiMnSb, and PtMnSb; some Si-containing half–Heusler alloys with Curie temperatures over 600 K, such as NiCrSi and PdCrSi; some transition-metal oxides, including rutile structured CrO2; some perovskites, such as LaMnO3 and SeMnO3; and a few more simply structured zincblende (ZB) compounds, including CrAs and superlattices. NiMnSb and CrO2 have been experimentally determined to be half-metals at very low temperatures.
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 <a href="/facts/Manganese/j9ELd1TL">manganese</a>-based <a href="/facts/Heusler_alloy/12ro9MxT">Heusler alloys</a>.
Some notable half-metals are <a href="/facts/Chromium(IV)_oxide/vd0nDFom">chromium(IV) oxide</a>, <a href="/facts/Magnetite/SVxoGUs2">magnetite</a>, and <a href="/facts/Lanthanum_strontium_manganite/1dDlwSfL">lanthanum strontium manganite</a> (LSMO), as well as chromium arsenide. Half-metals have attracted some interest for their potential use in <a href="/facts/Spintronics/dAWl8rcI">spintronics</a>.

Half-metal open-in-new

Half-metal