Ultrafast Terahertz Conductivity Probes of Topologically Enhanced Surface Transport Driven by Mid-Infrared Laser Pulses in Bi${}_2$Se${}_3$

Abstract

The recent discovery of topology-protected charge transport of ultimate thinness on surfaces of three-dimensional topological insulators (TIs) are breaking new ground in fundamental quantum science and transformative technology. Yet a challenge remains on how to isolate and disentangle helical spin transport on the surface from bulk conduction. Here we show that selective midinfrared femtosecond photoexcitation of exclusive intraband electronic transitions at low temperature underpins topological enhancement of terahertz (THz) surface transport in doped Bi2Se3, with no complication from interband excitations or need for controlled doping. The unique, hot electron state is characterized by conserved populations of surface/bulk bands and by frequency-dependent hot carrier cooling times that directly distinguish the faster surface channel than the bulk. We determine the topological enhancement ratio between bulk and surface scattering rates, i.e., ${\gamma }_{\text{BS}}/{\gamma }_{\text{SS}}\sim$3.80 in equilibrium. These behaviors are absent at elevated lattice temperatures and for high pumpphoton frequencies and uences. The selective, mid-infrared-induced THz conductivity provides a new paradigm to characterize TIs and may apply to emerging topological semimetals in order to separate the transport connected with the Weyl nodes from other bulk bands.

arXiv commentPaper in review

References in corpus (28)

• Topological Insulators
• $Z_2$ Topological Order and the Quantum Spin Hall Effect
• A topological Dirac insulator in a quantum spin Hall phase : Experimental observation of first strong topological insulator
• Topological invariants of time-reversal-invariant band structures
• First observation of Spin-Momentum Helical Locking in Bi2Se3 and Bi2Te3, demonstration of Topological-Order at 300K and a realization of topological-transport-regime
• Topological Materials: Weyl Semimetals
• Crossover of Three-Dimensional Topological Insulator of Bi2Se3 to the Two-Dimensional Limit
• The quantum spin Hall effect and topological insulators
• Topological response in Weyl semimetals and the chiral anomaly
• The Helical Liquid and the Edge of Quantum Spin Hall Systems
• Lieb-Robinson bounds and the generation of correlations and topological quantum order
• Massive Dirac fermions and spin physics in an ultrathin film of topological insulator
• Oscillatory crossover from two dimensional to three dimensional topological insulators
• Ultrafast Optical Excitation of a Persistent Surface-State Population in the Topological Insulator Bi2Se3
• Quantized Faraday and Kerr rotation and axion electrodynamics of a 3D topological insulator
• Anomalous Finite Size Effects on Surface States in the Topological Insulator Bi${}_2$Se${}_3$
• Measurement of intrinsic Dirac fermion cooling on the surface of a topological insulator Bi${}_2$Se${}_3$ using time- and angle-resolved photoemission spectroscopy
• A sudden collapse in the transport lifetime across the topological phase transition in $(B{i}_{1-x}I{n}_x{)}_{2}S{e}_3$
• THz response and colossal Kerr rotation from the surface states of the topological insulator Bi${}_2$Se${}_3$
• Observation of the universal magnetoelectric effect in a 3D topological insulator
• Strong nonlinear terahertz response induced by Dirac surface states in Bi2Se3 Topological Insulator
• Record Surface State Mobility and Quantum Hall Effect in Topological Insulator Thin Films via Interface Engineering
• Time-resolved terahertz dynamics in thin films of the topological insulator Bi${}_2$Se${}_3$
• Ultrafast observation of critical nematic fluctuations and giant magnetoelastic coupling in iron pnictides
• Generation of Transient Photocurrents in the Topological Surface State of Sb${}_2$Te${}_3$ by Direct Optical Excitation with Mid-Infrared Pulses
• Ultrafast terahertz probes of interacting dark excitons in chirality-specific semiconducting single-walled carbon nanotubes
• Non-equilibrium Pair Breaking in Ba(Fe1-xCox)2As2 Superconductors: Evidence for Formation of Photo-Induced Excitonic Spin-Density-Wave State
• Influence of Helical Spin Structure on the Magnetoresistance of an Ideal Topological Insulator

Cited by in corpus (30)

• Topology and geometry under the nonlinear electromagnetic spotlight
• Light-Driven Raman Coherence as a Non-Thermal Route to Ultrafast Topology Switching
• Discovery of Terahertz Second Harmonic Generation from Lightwave Acceleration of Symmetry--Breaking Nonlinear Supercurrents
• Generation of high-quality terahertz OAM mode based on soft-aperture difference frequency generation
• Terahertz signatures of ultrafast Dirac fermion relaxation at the surface of topological insulators at room temperature
• Clarifying ultrafast carrier dynamics in ultrathin films of the topological insulator Bi2Se3 using transient absorption spectroscopy
• Ultrafast Control of Excitonic Rashba Fine Structure by Phonon Coherences in a Metal Halide Perovskite CH${}_3$NH${}_3$PbI${}_3$
• Competing Orders and Ultrafast Energy Transfer at the Quantum Limit in a Nb${}_3$Sn Superconductor Probed by Terahertz Electrodynamics
• Cryogenic Magneto-Terahertz Scanning Near-field Optical Microscope (cm-SNOM)
• Coherent Band-Edge Oscillations and Dynamic LO Phonon Mode Splitting as Evidence for Polaronic Coupling in Perovskites
• Dynamical separation of bulk and edge transport in HgTe-based 2D topological insulators
• Lightwave Terahertz Quantum Manipulation of Non-equilibrium Superconductor Phases and their Collective Modes
• Ultrafast carrier-lattice interactions and interlayer modulations of Bi2Se3 by X-ray free electron laser diffraction
• Chirality manipulation of ultrafast phase switchings in a correlated CDW-Weyl semimetal
• Multi-Dimensional Coherent Spectroscopy of Light-Driven States and their Collective Modes in Multi-Band Superconductors
• Visualizing heterogeneous dipole fields by terahertz light coupling in individual nano-junctions used in transmon qubits
• Two-dimensional coherent spectrum of high-spin models via a quantum computing approach
• Quantum Liouville's theorem based on Haar measure
• Multiphoton-pumped UV-Vis transient absorption spectroscopy of 2D materials: basic concepts and recent applications
• Relaxation dynamics of the optically driven nonequilibrium states in the electron- and hole-doped topological-insulator materials $(B{i}_{1-x}S{b}_x{)}_{2}T{e}_3$
• Geometric pumping and dephasing at topological phase transition
• Adaptive variational quantum computing approaches for Green's functions and nonlinear susceptibilities
• Two-photon IR pumped UV-Vis transient absorption spectroscopy of Dirac fermions in the 2D and 3D topological insulator Bi2Se3
• Ultrafast transient absorption spectroscopy of 2D semiconductors: a review
• Ultrafast switching of topological invariants by light-driven strain
• Unveiling Symmetry Instability induced by Topological Phase Transitions
• Coherent Transfer of Lattice Entropy via Extreme Nonlinear Phononics in Metal Halide Perovskites
• Band structure of Bi surfaces formed on Bi2Se3 upon exposure to air
• Dirac plasmon polaritons and magnetic modes in topological-insulator nanoparticles
• Research on topological materials using ultrafast spectroscopy