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. These oscillations were assigned to the transverse magnetic and transverse electric guided CADP modes induced by the evanescent guided Lamb acoustic waves and remained Landau undamped due to fermion tunneling between the opposite-surface Dirac states.

References in corpus (10)

• Theory of surface plasmons and surface-plasmon polaritons
• Phase transition between the quantum spin Hall and insulator phases in 3D: emergence of a topological gapless phase
• Coexistence of the topological state and a two-dimensional electron gas on the surface of Bi2Se3
• Bulk Fermi surface coexistence with Dirac surface state in Bi${}_2$Se${}_3$: a comparison of photoemission and Shubnikov-de Haas measurements
• Nonlinear optical probe of tunable surface electrons on a topological insulator
• Emergence of decoupled surface transport channels in bulk insulating Bi2Se3 thin films
• Effect of carrier recombination on ultrafast carrier dynamics in thin films of the topological insulator Bi2Se3
• Thermoelectric performance of classical topological insulator nanowires
• Acoustic phonon dynamics in thin-films of the topological insulator Bi2Se3
• Resonance-type thickness dependence of optical second harmonic generation in thin-films of the topological insulator Bi2Se3

Cited by in corpus (7)

• Tunable Intrinsic Plasmons due to Band Inversion in Topological Materials
• Coherent surface-to-bulk vibrational coupling in the 2D topologically trivial insulator Bi2Se3 monitored by ultrafast transient absorption spectroscopy
• Dynamic Opening of a Gap in Dirac Surface States of the Thin-Film 3D Topological Insulator Bi2Se3 Driven by the Dynamic Rashba Effect
• Multiphoton-pumped UV-Vis transient absorption spectroscopy of 2D materials: basic concepts and recent applications
• Ultrafast transient absorption spectroscopy of 2D semiconductors: a review
• Two-photon IR pumped UV-Vis transient absorption spectroscopy of Dirac fermions in the 2D and 3D topological insulator Bi2Se3
• Chiral edge plasmons in quantum anomalous Hall insulators