Signatures of long-range-correlated disorder in the magnetotransport of ultrathin topological insulators

Abstract

In an ultrathin topological insulator (TI) film, a hybridization gap opens in the TI surface states, and the system is expected to become either a trivial insulator or a quantum spin Hall insulator when the chemical potential is within the hybridization gap. Here we show, however, that these insulating states are destroyed by the presence of a large and long-range-correlated disorder potential, which converts the expected insulator into a metal. We perform transport measurements in ultrathin, dual-gated topological insulator films as a function of temperature, gate voltage, and magnetic field, and we observe a metallic-like, non-quantized conductivity, which exhibits a weak antilocalization-like cusp at the low magnetic field and gives way to a nonsaturating linear magnetoresistance at large field. We explain these results by considering the disordered network of electron- and hole-type puddles induced by charged impurities. We argue theoretically that such disorder can produce an insulator-to-metal transition as a function of increasing disorder strength, and we derive a condition on the band gap and the impurity concentration necessary to observe the insulating state. We also explain the linear magnetoresistance in terms of strong spatial fluctuations of the local conductivity, using both numerical simulations and a theoretical scaling argument.

arXiv comment13 pages, 14 figures

References in corpus (41)

• Topological Insulators
• Quantum Spin Hall Insulator State in HgTe Quantum Wells
• Superconducting proximity effect and Majorana fermions at the surface of a topological insulator
• Experimental Observation of the Quantum Anomalous Hall Effect in a Magnetic Topological Insulator
• First observation of Spin-Momentum Helical Locking in Bi2Se3 and Bi2Te3, demonstration of Topological-Order at 300K and a realization of topological-transport-regime
• Crossover of Three-Dimensional Topological Insulator of Bi2Se3 to the Two-Dimensional Limit
• Observation of the fractional ac Josephson effect: the signature of Majorana particles
• Seeing the magnetic monopole through the mirror of topological surface states
• Magnetoelectric polarizability and axion electrodynamics in crystalline insulators
• Nonlocal edge state transport in the quantum spin Hall state
• Band structure engineering in (Bi1-xSbx)2Te3 ternary topological insulators
• Oscillatory crossover from two dimensional to three dimensional topological insulators
• Manipulation of Majorana fermion, Andreev reflection and Josephson current on topological insulators
• Finite size effects of helical edge states in HgTe/CdTe quantum wells
• Spin Polarization and Transport of Surface States in the Topological Insulators Bi2Se3 and Bi2Te3 from First Principles
• Energy gaps in etched graphene nanoribbons
• Unconventional Josephson Effect in Hybrid Superconductor-Topological Insulator Devices
• Induced Superconductivity in the Quantum Spin Hall Edge
• Crossover between weak localization and weak antilocalization in magnetically doped topological insulator
• Electrically tunable surface-to-bulk coherent coupling in topological insulator thin films
• Optimizing the Bi_(2-x)Sb_(x)Te_(3-y)Se_(y) solid solutions to approach the intrinsic topological insulator regime
• Thickness-dependent bulk properties and weak anti-localization effect in topological insulator Bi2Se3
• Tunable Surface Conductivity in Bi2Se3 Revealed in Diffusive Electron Transport
• Classical magnetotransport of inhomogeneous conductors
• Landau quantization and the thickness limit of topological insulator thin films of Sb2Te3
• Evidence for an anomalous current phase relation in topological insulator Josephson junctions
• Mapping the chemical potential dependence of current-induced spin polarization in a topological insulator
• Linear magnetoresistance on the topological surface
• Conformal Invariance and Shape-Dependent Conductance of Graphene Samples
• Anomalous Supercurrent from Majorana States in Topological Insulator Josephson Junctions
• Disorder induced magnetoresistance in a two dimensional electron system
• Weak Localization Effects as Evidence for Bulk Quantization in Thin Films Bi2Se3
• Unconventional Planar Hall Effect in Exchange-Coupled Topological Insulator-Ferromagnetic Insulator Heterostructures
• Effect of bulk charged impurities on the bulk and surface transport in three-dimensional topological insulators
• Bound state energy of a Coulomb impurity in gapped bilayer graphene: "Hydrogen atom with a Mexican hat"
• Equivalence of Effective Medium and Random Resistor Network models for disorder-induced unsaturating linear magnetoresistance
• Dirac-Electrons-Mediated Magnetic Proximity Effect in Topological Insulator / Magnetic Insulator Heterostructures
• Transport in two-dimensional disordered semimetals
• The longitudinal resistance of a quantum Hall system with a density gradient
• Continuous and reversible tuning of the disorder-driven superconductor-insulator transition in bilayer graphene
• Logarithmic singularities and quantum oscillations in magnetically doped topological insulators

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• Confinement-Induced Chiral Edge Channel Interaction in Quantum Anomalous Hall Insulators
• Conductivity of two-dimensional narrow gap semiconductors subjected to strong Coulomb disorder
• Disorder effects in topological insulator thin films
• Ferromagnetic phase transition in topological crystalline insulator thin films: interplay of anomalous Hall angle and magnetic anisotropy
• Absence of strong localization at low conductivity in the topological surface state of low disorder Sb2Te3
• Conductivity of a two-dimensional HgTe layer near the critical width: The role of developed edge states network and random mixture of $p$- and $n$-domains
• Conductivity of two-dimensional small gap semiconductors and topological insulators in strong Coulomb disorder
• Identifying the fingerprints of topological states by tuning magnetoresistance in a semimetal: the case of topological half-Heusler Pt1-xAuxLuSb
• Observation of the surface hybridization gap in the electrical transport properties of the ultrathin topological insulator (Bi${}_{1-x}$Sb${}_x$)${}_2$Te${}_3$
• Selective-Area Epitaxy of Bulk-Insulating (Bi${}_x$Sb${}_{1-x}$)${}_2$Te${}_3$ Films and Nanowires by Molecular Beam Epitaxy