2014/02/11 by Luis A. Jauregui, Jauregui, Luis A., Michael T. Pettes +8 · 1 citation
Materials Science · Physics and Astronomy · #FOS: Physical sciences #Graphene research and applications #Mesoscale and Nanoscale Physics (cond-mat.mes-hall) #Quantum and electron transport phenomena #Topological Materials and Phenomena
paper · pdf · doi:10.48550/arxiv.1402.2659
openalex publication_date 2014/02/11 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Transport due to spin-helical massless Dirac fermion surface state is of\nparamount importance to realize various new physical phenomena in topological\ninsulators, ranging from quantum anomalous Hall effect to Majorana fermions.\nHowever, one of the most important hallmarks of topological surface states, the\nDirac linear band dispersion, has been difficult to reveal directly in\ntransport measurements. Here we report experiments on Bi2Te3 nanoribbon\nambipolar field effect devices on high-k SrTiO3 substrates, where we achieve a\ngate-tuned bulk metal-insulator transition and the topological transport regime\nwith substantial surface state conduction. In this regime, we report two\nunambiguous transport evidences for gate-tunable Dirac fermions through \π\nBerry's phase in Shubnikov-de Haas oscillations and effective mass\nproportional to the Fermi momentum, indicating linear energy-momentum\ndispersion. We also measure a gate-tunable weak anti-localization (WAL) with 2\ncoherent conduction channels (indicating 2 decoupled surfaces) near the charge\nneutrality point, and a transition to weak localization (indicating a collapse\nof the Berry's phase) when the Fermi energy approaches the bulk conduction\nband. The gate-tunable Dirac fermion topological surface states pave the way\ntowards a variety of topological electronic devices.\n