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American Physical Society, Physical Review Letters, 17(110)

DOI: 10.1103/physrevlett.110.176802

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Topologically protected quantum transport in locally exfoliated bismuth at room temperature

Journal article published in 2013 by C. Sabater ORCID, D. Gosálbez-Martínez, J. Fernández-Rossier ORCID, J. G. Rodrigo, C. Untiedt ORCID, J. J. Palacios ORCID
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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 K and 300 K. As a function of the elongation of the nanocontact we measure robust, tens of nanometers long plateaus of conductance G0 = 2e^2/h at room temperature. This observation can be accounted for by the mechanical exfoliation of a Bi(111) bilayer, a predicted 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 break-up at both temperatures. Our finding provides the first experimental evidence of the possibility of mechanical exfoliation of Bi bilayers, of the existence of the QSH phase in a two-dimensional crystal, and, most importantly, of the observation of the QSH phase at room temperature. ; Comment: Accepted in Physical Review Letters. Supplemental Material upon request