Boron layers could set a superconductivity record, theoretical study predicts

Scientists in China have theorized that stacking two atomic layers of boron could potentially break the current record for superconductivity. Traditional superconductors require temperatures close to absolute zero and expensive cooling systems. The new research, published in Physical Review Letters, suggests that a single-element superconductor made entirely of boron could work at a much higher temperature.

If validated experimentally, this could drastically reduce cooling costs and boost the efficiency of power grids and technologies like medical imaging and maglev trains. The current best-known elemental superconductor, scandium, reaches 36 Kelvin (-237°C/-395°F) under about 260 gigapascals of pressure. The new prediction for the stacked boron layers is a threshold of 68 Kelvin (-205°C/-337°F) at normal atmospheric pressure.

To arrive at this prediction, the researchers used advanced computer simulations to model thousands of different arrangements of the ultra-thin boron layers, known as borophene. The most promising structure featured direct boron-boron bonds linking the two layers, which altered how the material vibrated and strengthened the interactions that enable electrons to pair up and move freely at higher temperatures.

The team ran calculations on over 9,000 different structural arrangements to identify the optimal one. The best-performing arrangement, known as an AA-stacked bilayer borophene, was predicted to achieve a superconducting temperature of 68 K at normal atmospheric pressure. The researchers noted that this finding sets a new benchmark for elemental superconductivity, surpassing the transition temperatures of all known elemental systems under both ambient and high pressure.

A key aspect of this work is the underlying mechanism. Unlike typical two-dimensional materials held together by weak interactions, the borophene layers are bonded by strong covalent boron-boron bonds, which changed how the atoms vibrated and opened a new route to achieving superconductivity at higher temperatures. The researchers emphasize that these are theoretical predictions based on computer modeling, and experimental validation in a laboratory setting will be crucial to confirm the findings.