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, $\mathrm{Sb})_{2}(\mathrm{Se}, \mathrm{Te})_{3}$ 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 Bi
2
Se
3
has the highest Q value among graphene or topological insulator below 1 THz.