Emergence of decoupled surface transport channels in bulk insulating Bi2Se3 thin films

Abstract

In ideal topological insulator (TI) films the bulk state, which is supposed to be insulating, should not provide any electric coupling between the two metallic surfaces. However, transport studies on existing TI films show that the topological states on opposite surfaces are electrically tied to each other at thicknesses far greater than the direct coupling limit where the surface wavefunctions overlap. Here, we show that as the conducting bulk channels are suppressed, the parasitic coupling effect diminishes and the decoupled surface channels emerge as expected for ideal TIs. In Bi2Se3 thin films with fully suppressed bulk states, the two surfaces, which are directly coupled below ~10 QL, become gradually isolated with increasing thickness and are completely decoupled beyond ~20 QL. On such a platform, it is now feasible to implement transport devices whose functionality relies on accessing the individual surface layers without any deleterious coupling effects.

Accepted for publication in Physical Review Letters

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Cited by in corpus (17)

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• Observation of Anderson localization in ultrathin films of three-dimensional topological insulators
• Effect of carrier recombination on ultrafast carrier dynamics in thin films of the topological insulator Bi2Se3
• Enhanced electron dephasing in three-dimensional topological insulators
• Experimental evidence and control of the bulk-mediated intersurface coupling in topological insulator Bi2Te2Se nanoribbons
• Nonlinear Optical Observation of Coherent Acoustic Dirac Plasmons in Thin-Film Topological Insulators
• Acoustic phonon dynamics in thin-films of the topological insulator Bi2Se3
• Bulk-Free Topological Insulator Bi2Se3 nanoribbons with Magnetotransport Signatures of Dirac Surface States
• Solution to the hole-doping problem and tunable quantum Hall effect in Bi${}_2$Se${}_3$ thin films
• Thickness tunable quantum interference between surface phonon and Dirac plasmon states in thin-films of the topological insulator Bi2Se3
• Stoichiometry-induced ferromagnetism in altermagnetic candidate MnTe
• Disorder-driven topological phase transition in Bi2Se3 films
• Coexistence of bulk and surface states probed by Shubnikov-de Haas oscillations in Bi${}_2$Se${}_3$ with high charge-carrier density
• Coupling-decoupling of conducting topological surface states in thick Bi${}_2$Se${}_3$ single crystals
• Evidence of decoupling of surface and bulk states in Dirac semimetal $C{d}_{3}A{s}_2$
• In-depth Analysis of Anisotropic Magnetoconductance in Bi${}_2$Se${}_3$ thin films with electron-electron interaction corrections
• Interfacing topological insulators and ferrimagnets: Bi${}_2$Te${}_3$ and Fe${}_3$O${}_4$ heterostructures grown by molecular beam epitaxy