Probing Dirac Fermion Dynamics in Topological Insulator Bi${}_2$Se${}_3$ Films with Scanning Tunneling Microscope

Abstract

Scanning tunneling microscopy and spectroscopy have been used to investigate the femtosecond dynamics of Dirac fermions in the topological insulator Bi${}_2$Se${}_3$ ultrathin films. At two-dimensional limit, bulk electrons becomes quantized and the quantization can be controlled by film thickness at single quintuple layer level. By studying the spatial decay of standing waves (quasiparticle interference patterns) off steps, we measure directly the energy and film thickness dependence of phase relaxation length $l_{\varphi }$ and inelastic scattering lifetime $\tau$ of topological surface-state electrons. We find that $\tau$ exhibits a remarkable $(E-E_F{)}^{-2}$ energy dependence and increases with film thickness. We show that the features revealed are typical for electron-electron scattering between surface and bulk states.

5 pages, 4 figures, to be published in Physical Review Letters

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• Topological insulators and superconductors
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Cited by in corpus (7)

• Experimental search for one-dimensional edge states at surface steps of the topological insulator Bi${}_2$Se${}_3$: Distinguishing between effects and artifacts
• Spatially resolved Landau level spectroscopy of the topological Dirac cone of bulk-type Sb2Te3(0001): potential fluctuations and quasiparticle lifetime
• Lifetime and surface-to-bulk scattering off vacancies of the topological surface state in the three-dimensional strong topological insulators Bi2Te3 and Bi2Se3
• Experimental Observation of Bound States of 2D Dirac Electrons at Surface Steps of the Topological Insulator Bi${}_2$Se${}_3$
• Transport theory for electrical detection of the spin texture and spin-momentum locking of topological surface states
• Spin-polarized scanning tunneling microscopy measurement scheme for determining the quantum geometric tensor
• Real-space visualization of quasiparticle dephasing near the Planckian limit in the Dirac line node material ZrSiS