Evolution of the topologically protected surface states in superconductor β-BiPd from the three-dimensional to the two-dimensional limit.

The recent discovery of topologically protected surface states in the noncentrosymmetric α-BiPd and the centrosymmetric β-[Formula: see text]Pd has renewed the interest in the Bi-Pd family of superconductors. We employ first-principles calculations to investigate the electronic structure and topological features of β-[Formula: see text]Pd, in bulk and in thin films of various thicknesses. We find that films of nine or more triple layers could harbor topological surface states with Dirac- and Rashba-like band dispersion.