science

Half-metal

Half-metal is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Half-metal rather than just read about it. In short: 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 (or ferrimagnetic), most ferromagnets are not half-metals.

Key takeaways

Half-metal belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Half-metal to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Half-metal from memory before moving on to harder problems.

Reference excerpt

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 (or ferrimagnetic), most ferromagnets are not half-metals. Many of the known examples of half-metals are oxides, sulfides, or Heusler alloys. 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 manganese-based Heusler alloys. Some notable half-metals are chromium(IV) oxide, magnetite, and lanthanum strontium manganite (LSMO), as well as chromium arsenide. Half-metals have attracted some interest for their potential use in spintronics. In July 2025, researchers reported the first experimental realization of a two-dimensional (2D) half-metal: a bilayer FePd alloy grown on a Pd(001) substrate. This system, composed of only two atomic layers, exhibits complete spin polarization at the Fermi level, as demonstrated by momentum and spin-resolved photoelectron spectroscopy. The half-metallicity is confined to the two-atomic-layer limit and modulated by the Fe-Pd content within the bilayer. The FePd bilayer remains half-metallic at room temperature, is structurally robust, and exhibits tunable electronic properties through variation in Fe content. These features make it a promising platform for nanoscale spintronic applications such as spin filters and spin–orbit torque devices.

References

Further reading Guezlane, M; Baaziz, H; El Haj Hassan, F; Charifi, Z; Djaballah, Y (2016). "Electronic, magnetic and thermal properties of Co2CrxFe1−xX (X=Al, Si) Heusler alloys: First-principles calculations". Journal of Magnetism and Magnetic Materials. 414: 219–26. Bibcode:2016JMMM..414..219G. doi:10.1016/j.jmmm.2016.04.056. Son, Young-Woo; Cohen, Marvin L; Louie, Steven G (2006). "Half-metallic graphene nanoribbons". Nature. 444 (7117): 347–9. arXiv:cond-mat/0611600. Bibcode:2006Natur.444..347S. doi:10.1038/nature05180. PMID 17108960. S2CID 52851642. http://www-users.york.ac.uk/~ah566/research/half_metals.html http://www.tcd.ie/Physics/People/Michael.Coey/oxsen/newsletter/january98/halfmeta.htm

Illustrations

Half-metal: The electronic structure of a half-metal.

E

f

{\displaystyle E_{f}}

is the Fermi level,

N
(
E
)

{\displaystyle N(E)}

is the density of states for spin down (on the left) and spin up (on the right). In this case, the half-metal is conducting in the minority spin channel. — The electronic structure of a half-metal. E f {\displaystyle E_{f}} is the Fermi level, N ( E ) {\displaystyle N(E)} is the density of states for spin down (on the left) and spin up (on the right). In this case, the half-metal is conducting in the minority spin channel.

Worked examples

Example 1 — a first encounter with Half-metal

Start with the simplest possible case. Write down what Half-metal claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Half-metal before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Half-metal ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Half-metal

In research: Half-metal appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Half-metal in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Half-metal is common in secondary-school and first-year university syllabi. It links to neighbouring topics Condensed matter stubs, Metals, Spintronics, so understanding it makes those chapters shorter.
In everyday life: Look for Half-metal outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Half-metal in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Half-metal means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Half-metal out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Half-metal in simple terms?

Why does Half-metal matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Half-metal?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Half-metal.