User:Sparkyscience/Topological Insulators

Certain insulators have exotic metallic states on their surfaces. These states are formed by topological effects that also render the electrons travelling on such surfaces insensitive to scattering by impurities. Such topological insulators may provide new routes to generating novel phases and particles, possibly finding uses in technological applications in spintronics and quantum computing.

Majorana fermions
Graphene

Axions
In 2008 Shoucheng Zhang and his colleagues showed that the equations that arise in axion physics are the same as those that describe the electromagnetic behaviour of a recently discovered class of materials known, collectively, as topological insulators.

History
Albert Einstein insisted that all fundamental laws of nature could be understood in terms of geometry and symmetry. Before 1980 all states of matter could be classified by the principle of broken symmetry. The quantum Hall state provided the first example of a state that had no spontaneously broken symmetry; its behaviour depended only on topology and not a specific geometry. The quantum Hall effect earned Klaus von Klitzing the Nobel Prize in Physics for 1985.

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