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Superconductors or custard slices?

Press release issued: 23 October 2003

A breakthrough has been made by researchers at Bristol University in understanding superconductors.

A breakthrough has been made by researchers at Bristol University in understanding superconductors. Their results, announced in the journal Nature today, contradict previous claims that electrons in individual layers of these mysterious materials do not communicate with each other, even though they are only atoms apart. These findings could have major implications for the future of technology.

High temperature superconductors are materials that can conduct electricity across huge distances without losing any energy. Technologists love them because they are relatively cheap to use. Scientists love them as they behave in weird and wonderful ways never seen before in metals.

Their structure consists of many layers stacked on top of each other. Electrons move easily between the different layers but, until now, flow across layers was thought to be impossible. This so-called "confinement" of electrons was considered to be at the centre of their unusual behaviour.

Dr Nigel Hussey, who led the research team at Bristol University, said: 'It's a bit like eating a custard slice. When you bite into it, the custard filling moves easily along the pastry layers but rarely across them. The electrons in high temperature superconductors behave in the same way - but occasionally they succeed in hopping from one layer to the next. This contradicts models which suggest they are totally confined to an individual plane.'

The research team from the Physics Department at Bristol University, used the world's strongest persistent magnetic field in Florida, USA, to study the motion of electrons in superconductors. Analysing their results within quantum theory, they observed a small but distinguishable motion of electrons between the different layers of the structure.

The puzzle now is to understand why the electronic properties of these high temperature superconductors are so unusual, given that electron confinement is no longer an issue.

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