X-rays reveal the role of inhomogeneity in superconductors

Picture: superconducting pairs running in the interstitial space between puddles
of electronic crystals (yellow bubbles)

Using synchrotron light techniques, an international research group showed that one of the best, high temperature (critical temperature Tc = 95 Kelvin) superconductor ceramic material displays a considerable complexity and heterogeneity, and that it is precisely this aspect which favors the superconducting state. These results described in an article published in the NATURE issue of 17 Sept 2015, are the outcome of a collaboration among researchers of many countries, coordinated by Gaetano Campi of the Italian Council of National Research, Antonio Bianconi of the Rome International Center for Material Science and Alessandro Ricci from Deutsches Elektronen-Synchrotron (DESY). 
The experimental part of the work has been performed in some of the most advanced experimental stations of dedicated X-Ray Diffraction beam lines at different synchrotron radiation facilities: European Synchrotron Radiation Facility, ESRF, at Grenoble, France; Elettra Sincrotrone Trieste facility at Basovizza, Italy; and DESY at Hamburg, Germany.

The authors demonstrated that below 250 K the electrons get organized within the material and they form nano puddles whose inhomogeneous distribution leave free interstitial spaces. The free electrons instead, organize themselves in pairs (Cooper pairs) at low temperatures, and flow in the free interstices between puddles.
Despite the fact that superconductivity is already employed in a variety of technologies, such as Magnetic Resonance Imaging, ultrafast CPUs, small particle detectors, electric motors and generators, we are still far from a large scale application, as the majority of today superconductors still need to be cooled to very low temperatures to show their properties - well below the first useful temperature for relatively less expensive technological applications which is the liquid nitrogen temperature, 70K.
Finding new materials superconducting at room temperature would transform our everyday life, allowing new technologies based on quantum physics. The problem is elusive for scientists since these phenomena need to be studied both at atomic and mesoscopic level and has been finally solved by a combination of scanning micro X-ray diffraction and temperature/time resolved diffraction experiments.

Published paper: Nature 525, 359–362 (17 September 2015) doi:10.1038/nature14987

Inhomogeneity of charge-density-wave order and quenched disorder in a high-Tc superconductor.

Authors: G. Campi, A. Bianconi, N. Poccia, G. Bianconi, L. Barba, G. Arrighetti, D. Innocenti, J. Karpinski, N. D. Zhigadlo, S. M. Kazakov, M. Burghammer, M. v. Zimmermann, M. Sprung & A. Ricci 




Last Updated on Friday, 25 September 2015 12:17