Nonlinear optical observation of coherent acoustic Dirac plasmons in thin-film topological insulators.

ABSTRACT: Low-energy collective electronic excitations exhibiting sound-like linear dispersion have been intensively studied both experimentally and theoretically for a long time. However, coherent acoustic plasmon modes appearing in time-domain measurements are rarely observed due to Landau damping by the single-particle continua. Here we report on the observation of coherent acoustic Dirac plasmon (CADP) modes excited in indirectly (electrostatically) opposite-surface coupled films of the topological insulator Bi₂Se₃. Using transient second-harmonic generation, a technique capable of independently monitoring the in-plane and out-of-plane electron dynamics in the films, the GHz-range oscillations were observed without corresponding oscillations in the transient reflectivity. T

SUBMITTER: Glinka YD 

PROVIDER: S-EPMC5056522 | biostudies-literature | 2016 Sep

REPOSITORIES: biostudies-literature