Half-metal
Encyclopedia
A half-metal is any substance that acts as a conductor
to electron
s of one spin
orientation, but as an insulator
to those of the opposite orientation.
Conduction in magnetic materials is due to two types of electron, i.e., electrons with spin up and electrons with spin down.
In half-metals, the valence band related to one type of these electrons is fully filled and the other is partially filled. So only one type of electrons (the spin type with the partially filled band) can pass through it, because full bands have a net conductance of zero.
A schematic diagram of the band structure of a half-metal is shown below.
Some notable half-metals are chromium(IV) oxide
and Perovskite
lanthanum strontium manganite
(LSMO); as well as chromium arsenide.
Electrical conductor
In physics and electrical engineering, a conductor is a material which contains movable electric charges. In metallic conductors such as copper or aluminum, the movable charged particles are electrons...
to electron
Electron
The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
s of one spin
Spin (physics)
In quantum mechanics and particle physics, spin is a fundamental characteristic property of elementary particles, composite particles , and atomic nuclei.It is worth noting that the intrinsic property of subatomic particles called spin and discussed in this article, is related in some small ways,...
orientation, but as an insulator
Electrical insulation
thumb|250px|[[Coaxial Cable]] with dielectric insulator supporting a central coreThis article refers to electrical insulation. For insulation of heat, see Thermal insulation...
to those of the opposite orientation.
Conduction in magnetic materials is due to two types of electron, i.e., electrons with spin up and electrons with spin down.
In half-metals, the valence band related to one type of these electrons is fully filled and the other is partially filled. So only one type of electrons (the spin type with the partially filled band) can pass through it, because full bands have a net conductance of zero.
A schematic diagram of the band structure of a half-metal is shown below.
Some notable half-metals are chromium(IV) oxide
Chromium(IV) oxide
Chromium dioxide or chromium oxide is a synthetic magnetic substance once widely used in magnetic tape emulsion. With the increasing popularity of CDs and DVDs, the use of chromium oxide has declined. However, it is still used in data tape applications for enterprise-class storage systems...
and Perovskite
Perovskite
A perovskite structure is any material with the same type of crystal structure as calcium titanium oxide , known as the perovskite structure, or XIIA2+VIB4+X2−3 with the oxygen in the face centers. Perovskites take their name from this compound, which was first discovered in the Ural mountains of...
lanthanum strontium manganite
Lanthanum strontium manganite
Lanthanum strontium manganite is an oxide ceramic material with the general formula La1-xSrxMnO3, where x describes the doping level and is usually in the range of 10-20%....
(LSMO); as well as chromium arsenide.