Davis¿s images revealed additional information. Aside from confirming the actual physics of high Tc superconductivity, the pictures also validated the so-called Swiss Cheese model, which describes the sizes and shapes of nonsuperconducting regions around the zinc impurities. And the pictures showed a fainter second, cross-shaped, quasiparticle cloud over the zinc impurities, which was rotated 45 degrees and three times larger than the first.
This mysterious feature is only one of several puzzles the group hopes to solve in future months. They plan to continue their work using different ceramic high Tc superconductors and impurities other than zinc. They will also test a new superconducting tip made for their STM. This tip, the first of its kind, is made from niobium and operates in a magnetic field as powerful as 7.2 Tesla. "No one knows the precise recipe for making new higher temperature superconductors," Davis says. But he is sure going to try to find it.