‘Accidental’ purple bronze find hints at warmer superconductivity

25 Jul 2016

A rather unusual property of purple bronze has been discovered by accident, with researchers hopeful it could lead to high-temperature superconductivity.

The development of superconductivity is the holy grail in materials science, with temperature, rather than elements, a real head-scratcher.


Getting warm

Future Human

It was previously thought that absolute zero (-273ºC) was needed to successfully develop materials that offered no resistance whatsoever. In April, this temperature heated up to just -125ºC when cuprates (copper oxides laced with other atoms) and Cooper pairs (a previously theoretical idea that bound electrons could exist in two possible states) emerged in studies.

Now it could get warmer, still, following the surprise discovery of an unconventional charge density wave (CDW) on the surface of purple bronze (lithium molybdenum).

CDWs share a common origin, often co-exist and can compete for dominance in certain materials. So this discovery, at temperatures up to -53ºC, could be something big.

Getting warmer

Iowa State University’s Adam Kaminski and his team found that purple bronze showed an ‘extraordinary’ increase of CDW transition temperature from -143°C to -53 °C, and a huge increase of energy gap at the surface.

Both are properties essential for CDW and high-temperature superconductivity, according to Kaminski, who said this was an “accidental but very exciting discovery”.

“We were studying this material because its one-dimensional structure makes it quite interesting. We saw strange things happening to the electronic band structure, but when we looked at the surface we were stunned by extraordinary enhancement of transition temperature and energy gap.”

Kaminski’s paper on the subject was published in APS Physics.

Purple crystal image via Shutterstock

Gordon Hunt was a journalist with Silicon Republic