• 1 Department of Physics, Georgetown University , Washington, District of Columbia 20057, United States
  • 2 Department of Physics and Astronomy, Northwestern University , Evanston, Illinois 60208, United States
  • 3 Kavli Institute of Nanoscience, Delft University of Technology , 2600 GA Delft, The Netherlands
  • 4 Department of Physics, CNAM, and JQI , University of Maryland , College Park, Maryland 20742, United States
Nano Lett., 2015 Dec 09;15(12):7859-66.
PMID: 26506109 DOI: 10.1021/acs.nanolett.5b02564


Van Hove singularities (VHSs) are a hallmark of reduced dimensionality, leading to a divergent density of states in one and two dimensions and predictions of new electronic properties when the Fermi energy is close to these divergences. In carbon nanotubes, VHSs mark the onset of new subbands. They are elusive in standard electronic transport characterization measurements because they do not typically appear as notable features and therefore their effect on the nanotube conductance is largely unexplored. Here we report conductance measurements of carbon nanotubes where VHSs are clearly revealed by interference patterns of the electronic wave functions, showing both a sharp increase of quantum capacitance, and a sharp reduction of energy level spacing, consistent with an upsurge of density of states. At VHSs, we also measure an anomalous increase of conductance below a temperature of about 30 K. We argue that this transport feature is consistent with the formation of Cooper pairs in the nanotube.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.