Surface states

Surface states refer to electronic states that exist at the surface of a material, particularly in solid-state physics and materials science. Unlike bulk states, which are found in the interior of a material, surface states arise due to the termination of the periodic potential created by the lattice of atoms in a solid. When the material's surface is exposed to the environment, the atoms at the surface are less coordinated compared to those in the bulk, leading to a distinct electronic structure.