Van Hove singularity and isotope effect in high-Tc copper oxides

• 摘要：

  Recently it was proposed that a very small oxygen-isotope effect in the high-Tc Cu oxides can be understood in terms of a logarithmic singularity in the density of states, N(E), near the Fermi energy, along with a conventional BCS phonon-mediated pairing. In this paper we show that a relatively realistic N(E), derived from a tight-binding model on two-dimensional lattices, contains a logarithmic term plus a constant term. The calculated result indicates that the additional constant term in N(E) makes the minimum for the isotope-mass exponent well exceed the corresponding experimental value (00.2). The interplanar hopping is shown to smear out the sharp peak of N(E) so that shifts further towards the standard BCS value of 1/2. So it appears to us that an explanation of the isotope effect as a function of doping in terms of a Van Hove singularity is not tenable. © 1991 The American Physical Society.

• 作者：

  Xing D. Y.;Gong C. D.;Liu M.

• 刊名：

  Physical Review B

• 在线出版时间：

  1991