Discovery in parent of one high-#temperature #superconductor may lead to predictive control

Brookhaven National Laboratory (DOE)
July 21, 2011

A team of scientists studying the parent compound of a cuprate (copper-oxide) superconductor has discovered a link between two different states, or phases, of that matter — and written a mathematical theory to describe the relationship. This work, appearing in the July 22, 2011, issue of Science, will help scientists predict the material’s behavior under varying conditions, and may help explain how it’s transformed into a superconductor able to carry current with no energy loss.

“The ultimate goal is to use what we learn to design copper-oxide materials with desired properties — such as superconductors that operate at temperatures warm enough to allow more widespread use in applications designed to transform the distribution of electricity,” said J.C. Séamus Davis, a co-author on the paper. Davis is Director of the Center for Emergent Superconductivity at the U.S. Department of Energy’s Brookhaven National Laboratory and the J.D. White Distinguished Professor of Physical Sciences at Cornell University.

“If you want to understand how to use a material, you need a theoretical understanding of how it behaves under different conditions,” Davis said. For example, there would be no desktop computers if we didn’t first have a theory to explain the behavior of silicon, the main component of the computer’s memory and processing chips. “To attain that kind of control over cuprate superconductors — materials that have enormous potential for improving energy efficiency and storage — we need that quantitative and predictive understanding.”

One challenge is that copper-oxide superconductors have lots of other states that can compete with superconductivity. To begin to understand these different phases — which are dominant, which are weaker, how they interact, and what happens to alter the balance of “power” — the experimentalists* on the team used a technique called spectroscopic image-scanning tunneling microscopy, developed by Davis, to directly visualize the electrons in each phase at the atomic level.
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