- A new class of material exhibits superconductivity at -23°C.
- The this is the new record for the highest-temperature superconductor, a jump of 50°C compared to the previous record.
Until the late 1980s, superconductivity was thought to be a low-temperature phenomenon, as all recognized superconducting materials had critical temperatures (Tc) less than -243°C.
The discovery of cuprate superconductors (material based on copper with higher Tc) attracted a lot of scientific attention. It inspired scientists to achieve superconductivity at room temperature. However, despite substantial studies and extensive researches, the maximum value of Tc remained almost the same for the next 2 decades.
In recent years, scientists have been able to bring down this value to -73°C. But since such a cool environment is expensive to maintain, they haven’t been able to utilize the full potential of superconductivity.
Now, researchers at the University of Chicago have analyzed a class of material in which they found superconductivity at -23°C, a jump of 50°C compared to the previous record.
Some recent theoretical calculations show that a new type of materials of superconducting hydrides could open doors for achieving superconductivity at higher temperatures. The team tested the superconductivity of this new material known as lanthanum superhydrides, and specified its structure and constituents.
However, there is a catch: the material must experience extremely high pressure, ranging from 150 to 170 gigapascals. To put this into perspective, the average sea-level pressure is about 101 kilopascals. Only under such conditions, the tiny material (few microns across) can exhibit superconductivity at -23°C. This is now the new record for the highest-temperature superconductor.
To better examine the material, researchers used Advanced Photon Source that provided high-energy, ultra-bright X-ray beams. They squeezed a very small material sample between 2 small pieces of diamonds to apply the required pressure, and then exploited X-rays to study the material’s structure and constituents.
This new material exhibited 3 (out of 4) properties essential for superconductivity.
- Electrical resistance was reduced.
- The critical temperature dropped under an external magnetic field.
- When some elements were replaced with different isotopes, the material changed its temperature.
- However, the Meissner effect — expulsion of a magnetic field when the material is in the process of becoming a superconductor — wasn’t observed.
Since the critical temperature of the new superconducting material falls within the normal range of various regions in the world, the next objective of 0°C now seems possible. Though the ultimate aim is to achieve superconductivity at room temperature.
Currently, the team is collaborating with other institutes to build more reasonable conditions for superconductivity. In the coming years, researchers will try to decrease the pressure required to create such materials, or at least, synthesize materials at high pressures that could exhibit superconductivity at normal pressures.