A breakthrough in controlling defects could lead to new generation of electronic devices
Reporting in Nature Materials this week, researchers from the Physics Department of Sapienza University of Rome and the London Centre for Nanotechnology have discovered a technique to ‘draw' superconducting shapes using an X-ray beam. This ability to create and control tiny superconducting structures has implications for a completely new generation of electronic devices.
Superconductivity is a special state where a material conducts electricity with no resistance, meaning absolutely zero energy is wasted.
The research group has shown that they can manipulate regions of high temperature superconductivity, in a particular material which combines oxygen, copper and a heavier, "rare earth" element, lanthanum. Illuminating with X-rays causes a small scale re-arrangement of the oxygen atoms in their material, resulting in high temperature superconductivity, of the type originally discovered for such materials 25 years ago by IBM scientists. The X-ray beam is then used like a pen to draw shapes in two dimensions.
A well as being able to write superconductors with dimensions much smaller than the width of a human hair, they are able to erase those structures by applying heat treatments. They now have the tools to write and erase with high precision, in very few simple steps and without the chemicals ordinarily used in device fabrication. This ability to re-arrange the underlying structure of a material in turn has wider applications to similar compounds containing metal atoms and oxygen, ranging from fuel cells to catalysts.
Prof. Aeppli, Director of the London Centre for Nanotechnology and the UCL investigator on the project, commented that
"Our validation of a one-step, chemical-free technique to generate superconductors opens up exciting new possibilities for electronic devices, particularly in re-writing superconducting logic circuits. Of profound importance is the key to solving the notorious ‘travelling salesman problem', which underlies many of the world's great computational challenges. We want to create computers on demand to solve this problem, with applications from genetics to logistics. A discovery like this means a paradigm shift in computing technology is one step closer."
Prof Bianconi, the leader of the team from Sapienza, added
"It is amazing that in a few simple steps, we can now add superconducting ‘intelligence' directly to a material consisting mainly of the common elements copper and oxygen."
The X-ray experiments were performed at the Elettra (Trieste) synchrotron radiation facility. The work is published in Nature Materials of 21 August 2011 (doi:10.1038/nmat3088) and follows on from previous discovery of fractal-like structures in superconductors (doi:10.1038/nature09260).
Figure: The experiments show that X-ray beams could be used in the future to write superconducting circuits, such as those depicted in the illustration. Here, solid lines indicate electrical connections while semicircles denote superconducting junctions, whose states are indicated by red arrows.
Professor Gabriel Aeppli is available for interview on: +44 207 679 0055 or email: lcn-administrator@ucl.ac.uk. Professor Antonio Bianconi is available for interview on: +39 338 843 8281 or email: antonio.bianconi@uniroma1.it
About the London Centre for Nanotechnology: The London Centre for Nanotechnology is an interdisciplinary joint enterprise between University College London and Imperial College London. In bringing together world-class infrastructure and leading nanotechnology research activities, the Centre has the critical mass to compete with the best facilities world-wide. Research programmes are aligned to three key areas, namely Planet Care, Healthcare and Information Technology and exploit core competencies in the biomedical, physical and engineering sciences.
About Sapienza University of Rome: The "Studium Urbis" was founded in 1303. In 1872 became the national university of the capital of Italy. Sapienza University is by far the largest university in Europe, with 140.000 students and more than 100 buildings. Enrico Fermi, Ettore Majorana, Ugo Fano and others have contributed to establish the Physics Department today as a leading centre of research and academic excellence
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