The BBVA Foundation Frontiers of Knowledge Award in Basic Sciences goes, in this eleventh edition, to Charles L. Kane and Eugene Mele, for their discovery of topological insulators, a new class of materials with extraordinary electronic properties: they are insulators in the interior, but their surface exhibits conductivity that is robust against perturbations.
Metallic materials conduct electricity whereas insulators do not. The standard picture was developed in the early days of quantum physics and is based on the band theory of solids. Kane and Mele predicted in 2005 that this simple classification fails for a new class of materials called topological insulators, whose existence was experimentally confirmed soon thereafter. These materials behave as conductors on the surface, but as insulators in the interior. Importantly, the surface conducting properties are fundamentally robust, and not affected by the presence of impurities or other perturbations. This robustness arises as long as certain symmetries are preserved and are a consequence of topology, a mathematical domain that explains, for example, why a sphere cannot be continuously deformed into a donut.
This surprising discovery opens up new scientific avenues in condensed matter physics and material science, such as the existence of new phases of matter and ways of manipulating their properties. Moreover, the basic principles behind topological insulators have important implications beyond condensed matter physics, for instance in the generation of efficient photonic and electronic devices, or quantum information processing.