Graphene-Based Topological Insulator with an Intrinsic Bulk Band Gap above Room Temperature

• Published in: Nano letters Vol. 13; no. 12; pp. 6251 - 6255
• Main Authors: Kou, Liangzhi, Yan, Binghai, Hu, Feiming, Wu, Shu-Chun, Wehling, Tim O, Felser, Claudia, Chen, Changfeng, Frauenheim, Thomas
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 11-12-2013
• Subjects: Applied sciences; Bismuth - chemistry; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Conduction band; Cross-disciplinary physics: materials science; rheology; Devices; Electron states and collective excitations in thin films, multilayers, quantum wells, mesoscopic and nanoscale systems; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronics; Exact sciences and technology; Fullerenes and related materials; diamonds, graphite; Graphene; Graphite - chemistry; Insulators; Low-dimensional structures (superlattices, quantum well structures, multilayers): structure, and nonelectronic properties; Magnetoelectric, magnetostrictive, magnetoacoustic, magnetooptic and magnetothermal devices. Spintronics; Materials science; Membranes, Artificial; Nanostructure; Nanostructures - chemistry; Physics; Quantum Dots - chemistry; Selenium - chemistry; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Specific materials; Surface Properties; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Temperature; Topology; Two dimensional; Topological insulator; large bandgap; strain engineering; quantum well; band inversion; graphene; Conduction bands; Electronic properties; Electrical properties; Backscattering; Hall effect; Nanostructures; Sandwich structures; III-V compound; Interfaces; Nanometer scale; Energy gap; Polarized spin; Graphene; J-J coupling; Spintronics; III-V semiconductors
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl4037214

Topological insulators (TIs) represent a new quantum state of matter characterized by robust gapless states inside the insulating bulk gap. The metallic edge states of a two-dimensional (2D) TI, known as the quantum spin Hall (QSH) effect, are immune to backscattering and carry fully spin-polarized dissipationless currents. However, existing 2D TIs realized in HgTe and InAs/GaSb suffer from small bulk gaps (<10 meV) well below room temperature, thus limiting their application in electronic and spintronic devices. Here, we report a new 2D TI comprising a graphene layer sandwiched between two Bi2Se3 slabs that exhibits a large intrinsic bulk band gap of 30–50 meV, making it viable for room-temperature applications. Distinct from previous strategies for enhancing the intrinsic spin–orbit coupling effect of the graphene lattice, the present graphene-based TI operates on a new mechanism of strong inversion between graphene Dirac bands and Bi2Se3 conduction bands. Strain engineering leads to effective control and substantial enhancement of the bulk gap. Recently reported synthesis of smooth graphene/Bi2Se3 interfaces demonstrates the feasibility of experimental realization of this new 2D TI structure, which holds great promise for nanoscale device applications.