Letter abstract

Nature Physics 6, 109 - 113 (2010)
Published online: 29 November 2009 | doi:10.1038/nphys1463

Subject Categories: Condensed-matter physics | Electronics, photonics and device physics | Nanotechnology

Observation of Van Hove singularities in twisted graphene layers

Guohong Li1, A. Luican1, J. M. B. Lopes dos Santos2, A. H. Castro Neto3, A. Reina4, J. Kong5 & E. Y. Andrei1


Electronic instabilities at the crossing of the Fermi energy with a Van Hove singularity1 in the density of states often lead to new phases of matter such as superconductivity2, 3, magnetism4 or density waves5. However, in most materials this condition is difficult to control. In the case of single-layer graphene, the singularity is too far from the Fermi energy6 and hence difficult to reach with standard doping and gating techniques7. Here we report the observation of low-energy Van Hove singularities in twisted graphene layers seen as two pronounced peaks in the density of states measured by scanning tunnelling spectroscopy. We demonstrate that a rotation between stacked graphene layers can generate Van Hove singularities, which can be brought arbitrarily close to the Fermi energy by varying the angle of rotation. This opens intriguing prospects for Van Hove singularity engineering of electronic phases.

  1. Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08855, USA
  2. CFP and Departamento de Física, Faculdade de Ciências Universidade do Porto, 4169-007 Porto, Portugal
  3. Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA
  4. Department of Materials Science and Engineering, MIT, Cambridge, Massachusetts 02139, USA
  5. Department of Electrical Engineering and Computer Science, MIT, Cambridge, Massachusetts 02139, USA

Correspondence to: E. Y. Andrei1 e-mail: eandrei@physics.rutgers.edu


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