Terahertz surface plasmon resonance in Dirac electron system topological insulator (Sb, Bi)2(Te, Se)3

Terahertz (THz) wave, corresponding to intermolecular binding energy, is the key to realize a non-labeling bio-medical sensor. We aim to enhance the sensitivity by a selective resonant excitation effect of the specific binding and surface plasmon at the THz band. Here, we report the THz-SPR of (Bi, Sb)(2)(Se, Te)(3) in both experiments and calculations for the first time. We have revealed that bulk electron influence seen in band structure may not contribute much to SPR, and Bi2Se3 has the highest Q value among graphene or topological insulator below 1 THz.