Super skinny superconductors promise faster electronic components

A new study has indicated that making superconductors super skinny suggests a new possible route to faster electronic components.

According to a report in New Scientist, Ivan Bozovic at Brookhaven National Laboratories in Upton, New York, and his team carried out the study.

"Making superconductors super-skinny raises the prospect of being able to switch them on and off using electric fields," said Bozovic.

That could allow them to be used in electronics, not just for carrying current from place to place.

"Static electric fields cannot penetrate more than 1 nanometre into good conductors," explained Bozovic.

So, a very thin superconductor indeed is needed to use electric fields in this way.

Physicists have long disagreed whether it is even possible for superconductivity to exist in such tight spaces, according to Bozovic.

Many have attempted to build very thin films from copper oxide-based materials called cuprates to find an answer. But, the roughness of the resulting films hampers their potential superconductive properties.

"Our approach is different," said Bozovic. His team created thicker films, but built them one atomic layer at a time.

They grew six layers of insulating lanthanum copper oxide, and above them six layers of metallic lanthanum-strontium copper oxide.

The way electrons leak between the two copper oxides spontaneously creates a superconducting layer somewhere within the stack, able to operate at the relatively high temperature of 32 kelvin (-241 degrees C) - most superconductors work at even lower temperatures.

The team made many versions of the superconducting layer cake with superconductor-suppressing zinc in different layers.

They were able to control the growth of each layer so finely that they could pinpoint the layer that was hiding the superconductivity.

Bozovic's team found that when they tainted the second lanthanum copper oxide layer in the stack, the critical temperature at which superconductivity could occur dropped from 32 kelvin to 18 kelvin.

No such temperature drop was seen if any other layer was doped with zinc.

"That proves that all of the "high-temperature" superconductivity traffic in the film takes place in a single copper oxide layer," said Bozovic.

The thin superconductor relies on other layers in the structure to feed it electrons.

But, according to Bozovic, in principle, the same effect is possible in a single layer of the material if electric fields are used.

That could produce high-temperature superconductivity in a single copper-oxide layer just 0.66 nanometres thick.