Anomalous Acoustic Plasmon Mode from Topologically Protected States

Abstract

Plasmons, the collective excitations of electrons in the bulk or at the surface, play an important role in the properties of materials, and have generated the field of Plasmonics. We report the observation of a highly unusual acoustic plasmon mode on the surface of a three-dimensional topological insulator (TI), Bi2Se3, using momentum resolved inelastic electron scattering. In sharp contrast to ordinary plasmon modes, this mode exhibits almost linear dispersion into the second Brillouin zone and remains prominent with remarkably weak damping not seen in any other systems. This behavior must be associated with the inherent robustness of the electrons in the TI surface state, so that not only the surface Dirac states but also their collective excitations are topologically protected. On the other hand, this mode has much smaller energy dispersion than expected from a continuous media excitation picture, which can be attributed to the strong coupling with surface phonons.

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Cited by in corpus (21)

• Phonons as a platform for non-Abelian braiding and its manifestation in layered silicates
• Topological phonons in oxide perovskites controlled by light
• Plasmonics in topological insulators: Spin-charge separation, the influence of the inversion layer, and phonon-plasmon coupling
• Multi-gap topology and non-Abelian braiding of phonons from first principles
• Observation of High-frequency Transverse Phonons in Metallic Glasses
• Hall and dissipative viscosity effects on edge magnetoplasmons
• Nanoscale Surface Dynamics of Bi${}_2$Te${}_3$(111): Observation of a Prominent Surface Acoustic Wave and the Role of van der Waals Interactions
• Tunable Intrinsic Plasmons due to Band Inversion in Topological Materials
• THz Surface Modes and Electron-Phonon Coupling in Bi${}_2$Se${}_3$(111)
• Surface Josephson plasma waves in a high-temperature superconductor
• Plasmon-polaron of the topological metallic surface states
• Plasmons in a two-dimensional nonsymmorphic nodal-line semimetal
• Topologically Nontrivial Interband Plasmons in Type-II Weyl Semimetal MoTe${}_2$
• Geometric Effect of High-Resolution Electron Energy Loss Spectroscopy on the Identification of Plasmons: An Example of Graphene
• Phase diagram and phonon-induced backscattering in topological insulator nanowires
• Electronic properties of the Dirac and Weyl systems with first- and higher-order dispersion in non-Fermi-liquid picture
• Two-photon IR pumped UV-Vis transient absorption spectroscopy of Dirac fermions in the 2D and 3D topological insulator Bi2Se3
• Impact of Electron-Phonon Interaction on Thermal Transport: A Review
• Chiral edge plasmons in quantum anomalous Hall insulators
• Observation of near EF Fermi-arc van Hove singularity with prominent coupling to phonon in a van der Waals coupled Weyl semimetal
• Evidence for atomic-scale vibron-mediated electron bunching