Scientists Finally Discover the Reason Behind the Unusual Behavior of These Superconductors

New advances have been made in superconductivity, providing fresh understanding into high-critical-temperature copper-based superconductors. The collaborative research shed light on the unusual metallic behavior of these superconductors and identified a critical point in quantum state. The breakthrough resulted from in-depth X-ray studies, offering potential for future tech solutions. Source: SciTechDaily.com

A recent study released critical findings on high-critical-temperature superconductors, pointing out their distinguished 'strange metal' phase and a vital quantum critical point. The results of the study, achieved through joint efforts and comprehensive experiments, indicate the future of advanced superconductive technologies.

The findings mark a notable development in superconductivity research. The generated understanding could promote the development of green technologies and contribute to an eco-friendly future.

A publication in Nature Communications by researchers from Politecnico di Milano, Chalmers University of Technology, and Sapienza University of Rome offer valuable insights into high-critical-temperature copper-based superconductors: they behave as 'strange' metals even above the critical temperature, meaning their electrical resistance shifts differently with temperature compared to ordinary metals.

The study suggests the existence of a quantum critical point related to the 'strange metal' phase.

The research presents a quantum critical point as a set of specific conditions where a substance experiences an abrupt change in its properties, solely due to quantum effects. "Like ice converting to liquid at zero degrees Celsius due to temperature effects on a microscopic level, cuprates transform into a 'strange' metal because of quantum charge fluctuations," noted Riccardo Arpaia, researcher at Chalmers' Department of Microtechnology and Nanoscience, and the primary author of the research.

The conclusions were based on X-ray scattering experiments performed at the European Synchrotron ESRF and the British synchrotron DLS. These experiments revealed the existence of charge density fluctuations impacting the electrical resistance of cuprates, making them 'strange.' Systematic tracking of how the energy of these fluctuations changes helped identify the quantity of the charge carrier density where this energy is minimum: the quantum critical point.

Giacomo Ghiringhelli, Professor at the Physics Department of the Politecnico di Milano, and the research’s coordinator, said, “This discovery is the culmination of more than five years of work. We employed a technique, known as RIXS, primarily developed by us at the Politecnico di Milano. Extensive data analysis and measurement campaigns enabled us to prove the existence of the quantum critical point. A deeper understanding of cuprates will inform the creation of better materials with higher critical temperatures, convenient for future technologies.”

Sergio Caprara, along with his fellow researchers at the Department of Physics of Sapienza University of Rome, proposed the theory attributing charge fluctuations a significant role in cuprates. He stated, “This discovery marks an essential progress in understanding not only the peculiar properties of the metallic state of cuprates, but also the still enigmatic mechanisms under high-temperature superconductivity.”

The research titled "Signature of quantum criticality in cuprates by charge density fluctuations" by Riccardo Arpaia et al was published in Nature Communications on November 8, 2023.