Researchers, including Steve Anlage, have discovered a new and simple experimental test to see if a superconductor is ‘unconventional’ and unusual. Many of the high temperature superconductors discovered over the past 30 years are thought to be unconventional in nature. One strategy for discovering new higher temperature superconductors is to create even more exotic unconventional superconductors. The experiment creates a clear graphical image of the properties of the superconductor in different directions, as shown below. An anisotropic image is a clear sign of the unconventional nature of the superconducting state. This image shows the four nodal directions of the d-wave superconductor YBa2Cu3O7- as enhanced response (tall, white areas). The technique can now be applied to newly discovered superconductors to test them for unconventional properties, and will help guide the search for even higher temperature superconductors.

The results appeared in a spring issue of Physical Review Letters.