A recent study published in Nature Communications has uncovered new insights into the behavior of high-critical-temperature copper-based superconductors. Researchers from Politecnico di Milano, Chalmers University of Technology, and Sapienza University of Rome have discovered that these superconductors exhibit unique properties even at temperatures above the critical temperature. These findings could revolutionize the field of superconductivity and contribute to the development of sustainable technologies for a more environmentally friendly future.
One of the intriguing observations made by the researchers is that these high-temperature superconductors behave like “strange” metals. Unlike normal metals, their electrical resistance changes in a different manner with temperature. This phenomenon has long puzzled scientists. The study suggests that this behavior is linked to the existence of a quantum critical point associated with the phase known as “strange metal.” The quantum critical point refers to specific conditions where a material undergoes a sudden change in its properties due solely to quantum effects. Just as ice melts into a liquid state at 0°C due to temperature effects, cuprates transform into a “strange” metal due to quantum charge fluctuations.
The researchers conducted X-ray scattering experiments at the European Synchrotron ESRF and the British synchrotron DLS to investigate the charge density fluctuations affecting the electrical resistance of cuprates. These fluctuations were found to make the cuprates exhibit “strange” metal behavior. By systematically measuring the energy variations of these fluctuations, the researchers were able to identify the charge carrier density at which the energy is minimized, i.e., the quantum critical point.
The discovery of the quantum critical point is the result of more than five years of dedicated research. The researchers utilized a technique called Resonant Inelastic X-ray Scattering (RIXS), which has been developed extensively at Politecnico di Milano. Through numerous measurement campaigns and innovative data analysis methods, they were able to confirm the existence of the quantum critical point in high-temperature superconductors. Understanding the behavior of cuprates will contribute to the design of improved materials with higher critical temperatures, making them easier to utilize in future technologies.
Sergio Caprara and his colleagues at the Department of Physics of Sapienza University of Rome proposed a theory that assigns a crucial role to charge fluctuations in cuprates. This theoretical framework provides a deeper understanding of the behavior of high-critical-temperature copper-based superconductors.
The recent study on high-critical-temperature copper-based superconductors has shed light on their “strange” metal behavior and the existence of a quantum critical point. This breakthrough has significant implications for the field of superconductivity and opens up new possibilities for sustainable technologies. Understanding the properties of cuprates will drive the development of improved materials with higher critical temperatures, leading to the widespread utilization of superconductors in future technologies. The collaborative efforts of researchers from Politecnico di Milano, Chalmers University of Technology, and Sapienza University of Rome have paved the way for advancements in the field and a more environmentally friendly future.
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