University researchers advance superconductor technology with new technique

Researchers at the University of Houston's Texas Center for Superconductivity have reached a significant milestone in their work towards achieving ambient-pressure high-temperature superconductivity. This development could pave the way for energy-efficient technologies that operate under everyday conditions.

The study, "Creation, stabilization, and investigation at ambient pressure of pressure-induced superconductivity in Bi0.5Sb1.5Te3," was published in the Proceedings of the National Academy of Sciences. Professors Liangzi Deng and Paul Ching-Wu Chu from the UH Department of Physics aimed to induce a superconducting state in BST by applying pressure without changing its chemistry or structure.

"In 2001, scientists suspected that applying high pressure to BST changed its Fermi surface topology, leading to improved thermoelectric performance," said Deng. "That connection between pressure, topology and superconductivity piqued our interest."

Chu added, "As materials scientist Pol Duwez once pointed out, most solids that are crucial to industry exist in a metastable state. The problem with that is many of the most exciting superconductors only work under pressure, making them difficult to study and even harder to use in practical applications."

Deng and Chu developed a technique called the pressure-quench protocol (PQP), which allows them to stabilize BST's high-pressure-induced superconducting states at ambient pressure. This breakthrough eliminates the need for special high-pressure environments.

"This experiment clearly demonstrates that one may stabilize the high-pressure-induced phase at ambient pressure via a subtle electronic transition without a symmetry change, offering a novel avenue to retain the material phases of interest and values that ordinarily exist only under pressure," Chu stated. "It should help our search for superconductors with higher transition temperatures."

Deng remarked, "Interestingly, this experiment revealed a novel approach to discovering new states of matter that do not exist at ambient pressure originally or even under high-pressure conditions. It demonstrates that PQP is a powerful tool for exploring and creating uncharted regions of material phase diagrams."

A multi-purpose measurement device used in these experiments can reach temperatures as low as 1.2 K (-457 F), utilizing an ultra-sensitive Magnetization Property Measurement System (MPMS) for precise magnetization measurements.