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Superconductivity achieved at room temperature

Press Trust of India  |  Berlin 

Researchers have for the first time succeeded in making a ceramic superconducting at room temperature without any need for cooling.

Superconductivity can transport electric current without any resistance and thus without any losses whatsoever.

With the aid of short infrared laser pulses, researchers made a ceramic superconducting at room temperature - albeit for only a few millionths of a microsecond.

An international team believes that laser pulses cause individual atoms in the crystal lattice to shift briefly and thus enhance the superconductivity.

The findings could assist in the development of materials which become superconducting at significantly higher temperatures and would thus be of interest for new applications, researchers said.

Superconductivity was known only in a few metals at temperatures just above absolute zero at minus 273 degrees Celsius.

In the 1980s, physicists discovered a new class, based on ceramic materials which conduct electricity at temperatures of around minus 200 degrees Celsius without losses, and were therefore called high-temperature superconductors.

One of these ceramics is the compound yttrium barium copper oxide (YBCO). The YBCO crystal has thin double layers of copper oxide alternate with thicker intermediate layers which contain barium as well as copper and oxygen.

In 2013, an international team working with researcher Andrea Cavalleri from Max Planck Institute for the Structure and Dynamics of Matter in Hamburg discovered that when YBCO is irradiated with infrared laser pulses it briefly becomes superconducting at room temperature.

"We started by again sending an infrared pulse into the crystal, and this excited certain atoms to oscillate," said Max Planck physicist Roman Mankowsky, lead author of the study.

The infrared pulse not only excited the atoms to oscillate, but also shifted their position in the crystal.

This briefly made the copper dioxide double layers thicker - by two picometres, or one hundredth of an atomic diameter - and the layer between them became thinner by the same amount.

This in turn increased the quantum coupling between the double layers to such an extent that the crystal became superconducting at room temperature for a few picoseconds.

The study was published in the journal Nature.

First Published: Sun, December 07 2014. 13:20 IST