Abstract
The electronic structures of Y Ba2Cu3Ox and YBa2Cu4O8 were studied by angleresolved photoemission with an energy resolution of better than 10 meV. A detailed study in the 1st and 2nd Brillouin zone of untwinned single crystals shows the presence of “extended” saddle point singularities in the band structure in the vicinity of the Fermi energy, which give rise to van Hove singularities in the density of states. The binding energy of the singularity depends on the do**. We show that this extended saddle point singularity leads to a density of states which diverges as ε−1/2, which in turn can lead to very high transition temperatures even in a BCS scheme with weak coupling.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
J.C. Campuzano, K. Gofron, R. Liu, H. Ding, B.W. Veal, and B. Dabrowski,J. Phys. Chem. Solids V53, 1577 (1992); K. Gofron, J.C. Campuzano, H. Ding, C. Gu, R. Liu, B. Dabrowski, B. Veal, W. Cramer and G. Jennings,J. Phys. Chem. Solids V54, 1193 (1993).
K. Gofron, J.C. Campuzano, H. Ding, A.A. Abrikosov, M. Lindroos, A. Bansil, and B. Dabrowski,To be published. A. Bansil, M. Lindroos, J.C. Campuzano and K. Gofron,J. Phys. Chem Solids V 54, 1185 (1993).
L. Van Hove,Phys. Rev. 89, 1189 (1953).
O.K. Andersen, A.I. Liechtenstein, O. Rodriguez, I.I. Mazin, O. Jepsen, V.P. Antropov, O. Gunnarsson, And S. Gopalan, PhysicaC 185, 147 (1991); S. Gopalan, O. Gunnarsson, And O.K. Andersen,Phys. Rev. 46, 11798 (1992).
J. E. Hirsh and D.J. Scalpino,Phys. Rev. Lett. 56, 2735 (1986).
J. Friedel,J. Phys.: Condens. Matter 1, 7757 (1989).
R.S. Markiewicz,Int. J. Mod. Phys. B 5, 2037 (1991); D. M. Newns et al.,Phys. Rev. Lett. 69, 1264 (1992); J. Labbe and J. Bok,Europhys. Lett. 3, 1225 (1987); J. Bok,Physica C 209, 107 (1993); L. Force et al.,Solid State Comm. 85, 975 (1993).
C. C. Tsuei et al.,Phys. Rev. Lett. 69, 2134 (1992); C. C. Tsuei et al.,Phys. Rev. Lett. 65, 2724 (1990); C. C. Tsuei et al.,Phys. Rev. Lett. 68, 1091 (1992); P.C. Pattnaik at al.,Phys. Rev. B 45, 5714 (1992).
A. A. Abrikosov, J.C. Campuzano, and K. Gofron,Phisica C 214, 73 (1993)
G. Manzke, R. Mante, R. Claessen, M. Skibowski and J. Fink,Surface Sci. 269, 1066 (1992), and references therein.
J.G. Tobin, C.G. Olson, C. Gu, J.Z. Liu, F.R. Solal, M.J. Fluss, R.H. Howell, J.C. Oubrien, H.B. Radousky and P.A. Sterne,Phys. Rev. B 45, 5563 (1992).
Author information
Authors and Affiliations
Additional information
This work was supported by DOE contract W-31-109-ENG-38 and NSF grants DMR 8914120 and DMR8809854. The Synchrotron Radiation Center is supported by NSF grant DMR 8601349.