The ability to achieve superconductivity at room temperature has taken a small step forward thanks to a recent discovery by a team of physicists and materials scientists at Penn State University. A surprising discovery was the superposition of a two-dimensional material called molybdenum sulfide on top of another material, molybdenum carbide. Molybdenum carbide is a well-known superconductor – electrons can flow through a material without any resistance. Even the best metals such as silver or copper lose energy due to heat. This loss makes transmission of electricity more expensive over long distances. A solution to this problem is explored in a study published in the journal Proceedings of the National Academy of Sciences.
Superconductivity is the property of some materials to have strictly zero electrical resistance when they reach a temperature below a certain value. Several hundreds of compounds, pure elements, alloys, and ceramics are known that go into a superconducting state.
This quantum phenomenon occurs at very low temperatures, close to absolute zero or 0 Kelvin (-273.15°C), while the alpha phase of molybdenum carbide is superconducting at 4 Kelvin (-269.15°C), said Mauricio Terrones, research author.
When the metastable phases of molybdenum carbide are layered on molybdenum sulfide, superconductivity arises already at 6 Kelvin. While this in itself is not remarkable – other materials are superconducting at temperatures up to 150 Kelvin – this phenomenon was unexpected. It heralds a new method for increasing superconductivity at higher temperatures in other superconducting materials.
A team of scientists used simulation techniques to understand how the effect occurred experimentally.
Calculations using quantum mechanics have helped in the interpretation of experimental measurements to determine the structure of molybdenum carbide and molybdenum sulfide. This work is a good example of how synthesis, characterization, and modeling of materials can come together to foster the discovery of new material systems with unique properties.
According to scientists, this is a fundamental discovery, although “no one believed that it would work”. The phenomenon that scientists observe has not been previously seen.
The research team will continue to experiment with superconducting materials. Their goal is someday to find combinations of materials that can transfer energy with zero resistance.