Unique duality: 'Exotic' superconductor with metallic surface discovered

Unique duality: 'Exotic' superconductor with metallic surface discovered: The new material -- a crystal called a topological superconductor -- has two electronic identities at once. At very low temperatures, the interior of the crystal behaves like a normal superconductor, able to conduct electricity with zero resistance. At the same time, the surface is metallic, able to carry a current, albeit with some resistance.