Shedding light on the strange metal regime of the cuprate superconductors

Chalmers researcher Riccardo Arpaia, Department of Microtechnology and Nanoscience, is one of the authors of a recently published article in Communications Physics – a new open access journal from Nature Research. The paper Strange metal behaviour from charge density fluctuations in cuprates is a result of a collaboration between Chalmers, Politecnico di Milano, Brandenburg University of Technology and a group of theoreticians at La Sapienza University in Rome. The new findings are based on Riccardo Arpaia’s research published in Science in 2019, within the framework of the "VR International Postdoc" carried out in Milan, Italy. 

This is the natural ‘sequel’ of the pioneering work published in 2019. There, the researchers experimentally showed, by X-ray scattering, a new property of cuprate superconductors - dynamic charge density fluctuations.

“The electrons in cuprate superconductors are strongly correlated. A fraction of them tend to self-organize, forming waves, and causing the electronic charge density to become spatially modulated.  Differently from other, previously discovered, electronic waves, ‘our’ charge density fluctuations have an extremely short correlation length, they do not seem to interfere with superconductivity and are present in a very broad range of doping and temperature, surviving at least up to room temperature. Among the others, this latter characteristic was extremely intriguing: being so pervasive, it was natural to ask ourselves if they could significantly affect the physics of this still mysterious class of compounds”, says Riccardo Arpaia, researcher at the Quantum Device Physics Laboratory at Chalmers.

In the work just published in Communication Physics, the researchers have presented a theoretical proposal, which has been developed by a group of theoreticians at La Sapienza University in Rome and at Brandenburg University of Technology. They have investigated the consequences of charge density fluctuations on the electron and transport properties of cuprates. The unforeseen discovery is that the charge density fluctuations allow them to explain one of the ‘strange’ (the use of such adjective is no coincidence!) characteristics of cuprates: the fact that, above the superconducting critical temperature, they have such a different behavior of the electrical resistance with respect to conventional metals. Which is indeed named ‘strange metal behavior’, and whose most evident benchmark is represented by the linear behaviour of the electrical resistivity as a function of the temperature T up to the highest attained temperatures.

“Charge density fluctuations are therefore likely the long-sought microscopic mechanism underlying the peculiarities of the metallic state of cuprates. This might represent a decisive step toward the understanding of this class of materials. Ultimately, indeed, the great interest in the scientific community is to grasp the secrets of high critical temperature superconductors, which might allow to build new superconductors, functioning close to room temperature and atmospheric pressure”

Read the paper in Communications Physics:

Page manager Published: Tue 26 Jan 2021.