Engineering quantum spin Hall insulators by strained-layer heterostructures

Abstract

Quantum spin Hall insulators (QSHIs), also known as two-dimensional topological insulators, have emerged as an unconventional class of quantum states with insulating bulk and conducting edges originating from nontrivial inverted band structures, and have been proposed as a platform for exploring spintronics applications and exotic quasiparticles related to the spin-helical edge modes. Despite theoretical proposals for various materials, however, experimental demonstrations of QSHIs have so far been limited to two systems--HgTe/CdTe and InAs/GaSb--both of which are lattice-matched semiconductor heterostructures. Here we report transport measurements in yet another realization of a band-inverted heterostructure as a QSHI candidate--InAs/In${}_x$Ga${}_{1-x}$Sb with lattice mismatch. We show that the compressive strain in the In${}_x$Ga${}_{1-x}$Sb layer enhances the band overlap and energy gap. Consequently, high bulk resistivity, two orders of magnitude higher than for InAs/GaSb, is obtained deep in the band-inverted regime. The strain also enhances bulk Rashba spin-orbit splitting, leading to an unusual situation where the Fermi level crosses only one spin branch for electronlike and holelike bands over a wide density range. These properties make this system a promising platform for robust QSHIs with unique spin properties and demonstrate strain to be an important ingredient for tuning spin-orbit interaction.

15 pages, 5 figures; added discussions

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Cited by in corpus (15)

• Effects of nuclear spins on the transport properties of the edge of two-dimensional topological insulators
• Helical Liquids in Semiconductors
• Low-Temperature Conductivity of Weakly Interacting Quantum Spin Hall Edges in Strained-Layer InAs/GaInSb
• First principles feasibility assessment of a topological insulator at the InAs/GaSb interface
• Strain tuned topology in the Haldane and the modified Haldane models
• Energy gap tuning and gate-controlled topological phase transition in InAs/In${}_x$Ga${}_{1-x}$Sb composite quantum wells
• Rashba Sandwiches with Topological Superconducting Phases
• Velocity and confinement of edge plasmons in HgTe-based 2D topological insulators
• Time-resolved measurement of ambipolar edge magnetoplasmon transport in InAs/InGaSb composite quantum wells
• On the impact of strain on the electronic properties of InAs/GaSb quantum well systems
• Quantum spin Hall effect in III-V semiconductors at elevated temperatures: advancing topological electronics
• Impact of epitaxial strain on the topological-nontopological phase diagram and semimetallic behavior of InAs/GaSb composite quantum wells
• Electrical tuning of helical edge states in topological multilayers
• Spin mixing between subbands and extraordinary Landau levels shift in wide HgTe quantum wells
• Microwave Photocurrent from the Helical Edge state of InAs/GaInSb Bilayers