The van Hove Singularity and Two-Dimensional Superconductivity. Exact Analytical Results |
| R. Szczęśniaka and S. Grabińskib aDepartment of Theoretical Physics, Institute of Physics University of Silesia, Uniwersytecka 4, 40-007 Katowice, Poland bSilesian Academy of Medicine, Institute of Biophysics 40-007 Katowice, Poland |
| Received: October 8, 2001; revised version March 11, 2002 |
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| We investigate a weak-coupling approach to superconductivity in the density of states that develops in the two-dimensional lattice with the van Hove singularity located at the Fermi level. Exact analytical expressions for the superconducting order parameter at zero temperature (Δ(0)) and for discontinuity in the specific heat at critical temperature (Δ C) were derived. We show that the presence of the logarithmic singularity hardly affects the ratio 2Δ(0)/kTc, whereas the temperature dependence of ΔC can pronouncedly deviate from the standard BCS result. |
| DOI: 10.12693/APhysPolA.102.401 PACS numbers: 74.25.Kc |