Observation of an "Extended" Van Hove Singularity in YBa2Cu4O8 by Ultrahigh Energy Resolution Angle-Resolved Photoemission

Phys. Rev. Lett. 73, 3302 – Published 12 December 1994
K. Gofron, J. C. Campuzano, A. A. Abrikosov, M. Lindroos, A. Bansil, H. Ding, D. Koelling, and B. Dabrowski


We characterize the nature of the Van Hove singularity near the Fermi energy (EF) in YBa2Cu4O8 using ultrahigh energy resolution (10 meV) angle-resolved photoemission spectroscopy, together with corresponding first-principles spectra intensity computations. The singularity, related to CuO2 planes, is located about 19 meV below EF at the Y point in the Brillouin zone and arises from a band which is nearly dispersionless along the Γ to Y direction. Such an "extended" saddle point would render the band structure quasi-1D and yield a power law divergence in the density of states, allowing the occurrence of Tc's of order 100 K even in a weak coupling BCS scheme.

DOI: http://dx.doi.org/10.1103/PhysRevLett.73.3302

  • Received 4 March 1994
  • Published in the issue dated 12 December 1994

© 1994 The American Physical Society

Authors & Affiliations

K. Gofron1,2, J. C. Campuzano1,2, A. A. Abrikosov1, M. Lindroos3,4, A. Bansil3, H. Ding1,2, D. Koelling1, and B. Dabrowski1,5

  • 1Argonne National Laboratory, 9700 S. Cass Ave, Argonne, Illinois 60439
  • 2Department of Physics, University of Illinois at Chicago, Chicago, Illinois 60607
  • 3Physics Department, Northeastern University, Boston, Massachusetts 02115
  • 4Physics Department, Tampere University of Technology, Tampere, Finland
  • 5Physics Department, Northern Illinois University, DeKalb, Illinois 60115

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