Researchers from the Texas Center for Superconductivity (TcSUH) and the University of Houston have set a remarkable new record in the field of superconductivity, achieving a superconducting transition temperature (Tc) of 151 Kelvin (approximately -122 degrees Celsius). This milestone represents the highest Tc ever documented for a superconductor operating at ambient pressure, a significant advancement since the discovery of superconductivity in 1911.
The transition temperature is crucial as it indicates the point at which a material can conduct electricity without resistance. Elevating this temperature has long been a primary focus in superconductivity research, as higher operating temperatures could make superconducting technologies more practical and economically viable.
Ching-Wu Chu and Liangzi Deng, the leading physicists behind this achievement, published their findings in the Proceedings of the National Academy of Sciences. The research received funding from Intellectual Ventures, the state of Texas via TcSUH, and various foundations.
"Electricity transmission through the grid results in approximately 8% loss," explained Chu, a professor of physics and founding director of TcSUH. "Conserving this energy could save billions of dollars and significantly reduce environmental impacts."
Importance of Superconductors
Superconductors are unique materials that allow electricity to flow without any resistance, thus preventing energy loss as heat. This characteristic could revolutionize the efficiency of electrical systems. They are also vital for advancements in technologies such as magnetic resonance imaging (MRI), fusion reactors, quantum computing, and ultrafast electronics.
However, many superconductors only function at extremely low temperatures, necessitating costly cooling systems that hinder widespread application.
"By achieving this at ambient pressure, we enhance accessibility for scientists to utilize established instrumentation for further exploration and technological development," noted Deng, assistant professor of physics and principal investigator at TcSUH.
Breaking a Long-Standing Barrier
The pursuit of superconductors with higher transition temperatures has been ongoing for decades. A significant leap occurred in 1987 when Chu and his team discovered that YBCO could become superconducting at -180 degrees Celsius (93 K), igniting global interest in high-temperature superconductors. In 1993, the mercury-based copper-oxide ceramic Hg1223 was found to achieve superconductivity at -140 degrees Celsius (133 K), a record that stood for over 30 years.
The new achievement from the University of Houston surpasses this record by 18 degrees Celsius, reaching 151 K.
Innovative Techniques for Stability
This breakthrough was made possible through a technique called pressure quenching. While pressure methods are commonly applied in various fields, their use in superconductivity research is relatively novel. The process involves applying high pressure to enhance superconducting properties before cooling the material at that pressure and then rapidly releasing it, preserving the enhanced state.
"Our findings indicate that maintaining superconductivity at room temperature under pressure is feasible, and our method demonstrates that this state can be retained without continuous pressure," Chu remarked.
A Vision for Room-Temperature Superconductors
While achieving room-temperature superconductivity at ambient pressure is still a goal, this new record is a significant step toward that ambition. Room temperature is around 300 K, leaving a gap of about 140 degrees Celsius to bridge.
"This discovery holds immense potential," Chu stated. "With collective efforts and time, we can realize this vision."
In a companion perspective paper also published in PNAS, Chu and Deng discuss various strategies for further increasing superconducting temperatures, including pressure quenching.
"Room-temperature superconductivity has been regarded as the 'holy grail' of science for over a century," said Rohit Prasankumar, director of superconductivity research at Intellectual Ventures. "The results from the UH team bring us closer to this goal, yet collaboration across the scientific community will be essential to close the remaining temperature gap."