surface states

Surface states are special electronic features that exist at the outermost layer of a material, like the surface of a crystal. While the interior (bulk) of the material has electrons distributed in regular patterns, at the surface, the atoms experience a different environment, creating unique energy levels. These surface states can conduct electricity differently and are crucial in phenomena like corrosion, catalysis, or the behavior of topological insulators. They play a key role in many advanced technologies because they influence how the surface interacts with light, electrons, or other materials.