Topologically Protected Quantum Transport in Locally Exfoliated Bismuth at Room Temperature

C. Sabater, D. Gosálbez-Martínez, J. Fernández-Rossier, J. G. Rodrigo, C. Untiedt, and J. J. Palacios
Phys. Rev. Lett. 110, 176802 – Published 23 April 2013
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Abstract

We report electrical conductance measurements of Bi nanocontacts created by repeated tip-surface indentation using a scanning tunneling microscope at temperatures of 4 and 300 K. As a function of the elongation of the nanocontact, we measure robust, tens of nanometers long plateaus of conductance G0=2e2/h at room temperature. This observation can be accounted for by the mechanical exfoliation of a Bi(111) bilayer, a predicted quantum spin Hall (QSH) insulator, in the retracing process following a tip-surface contact. The formation of the bilayer is further supported by the additional observation of conductance steps below G0 before breakup at both temperatures. Our finding provides the first experimental evidence of the possibility of mechanical exfoliation of Bi bilayers, the existence of the QSH phase in a two-dimensional crystal, and, most importantly, the observation of the QSH phase at room temperature.

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  • Received 11 October 2012

DOI:https://doi.org/10.1103/PhysRevLett.110.176802

© 2013 American Physical Society

Authors & Affiliations

C. Sabater1, D. Gosálbez-Martínez1, J. Fernández-Rossier2, J. G. Rodrigo3, C. Untiedt1, and J. J. Palacios3

  • 1Departamento de Física Aplicada, Universidad de Alicante, San Vicente del Raspeig, Alicante 03690, Spain
  • 2International Iberian Nanotechnology Laboratory, Avenida Mestre José Veiga, 4715-330 Braga, Portugal
  • 3Departamento de Física de la Materia Condensada and Instituto de Física de la Materia Condensada (IFIMAC), Universidad Autónoma de Madrid, Cantoblanco, Madrid 28049, Spain

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Issue

Vol. 110, Iss. 17 — 26 April 2013

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