Research raises temperature of superconductivity

The previous record for superconductivity in boron-doped diamond was 11 Kelvin (-439.60ºF). The boron-doped Q-carbon (an allotrope of carbon) has been found to be superconductive from 37K to 57K (-356.80°F).

“Going from 11K to 57K is a big jump for conventional BCS superconductivity,” said Jay Narayan, the John C. Fan Distinguished Chair Professor of Materials Science and Engineering at North Carolina State University and senior author of two papers describing the work. BCS refers to the Bardeen–Cooper–Schrieffer theory of superconductivity.

Regular conductive materials conduct electricity, but a lot of that energy is lost during transmission. Superconductors can handle much higher currents per square centimeter and lose virtually no energy through transmission. However, superconductors only have these desirable properties at low temperatures. Identifying ways to achieve superconductivity at higher temperatures – without applying high pressure – is an active area of materials research.

To make the boron-doped Q-carbon, the researchers coat a substrate with a mixture of amorphous carbon and boron. The mixture is then hit with a single laser pulse lasting for only a few nanoseconds. During this pulse, the temperature of the carbon is raised to 4,000 Kelvin and then rapidly quenched.