German researchers discover how superconductivity can be tapped to improve power transmission

August 20, 2012 // By Paul Buckley
An international team comprising physicists of the Max Planck Institute for Solid State Research in Stuttgart has discovered that a specific form of superconductivity competes with charge density waves, i.e. with a periodically fluctuating distribution of the charges.

Charge density waves improve our understanding of the zero-resistance transport of electricity and could explain an unusual interplay of superconducting and magnetic materials

Whether a material conducts electricity without losses is not least a question of the right temperature. In future it may be possible to make a more reliable prediction for high-temperature superconductors. These materials lose their resistance if they are cooled with liquid nitrogen, which is relatively easy to handle.

Since the physicists did not previously take account of this competition in their models, their calculations of the transition temperature, where superconductivity sets in, remained inaccurate. In further work, the researchers at the Stuttgart Max Planck Institute have gained insights into how superconducting materials interact with magnetic ones. The researchers observed that the electronic properties affect crystal vibrations to a greater extent than was to be expected. This effect could help to control material properties such as superconductivity or thermoelectricity.

If electricity from high-power offshore wind farms or even large-scale solar parks is to be distributed to consumers in future then quite a bit of energy will be lost in the long power lines. Superconducting cables could prevent this if cooling them does not consume more energy than they help to save. Bernhard Keimer and his colleagues at the Max Planck Institute for Solid State Research in Stuttgart want to identify materials that deserve the name high-temperature superconductor both in practical terms and also in terms of our usual perception of temperature. To do this they first have to understand how superconductivity works in these materials and how it can be influenced; these materials are known as high-temperature superconductors, even though they lose their resistance at temperatures which make a Siberian winter seem almost mild. The Stuttgart-based physicists have now taken a further step down this road in two current publications.

According to one of their discoveries we can probably consider ourselves lucky that high-temperature superconductivity - a