Role of vertex corrections in the spin-fluctuation-mediated pairing mechanismZ. B. Huang1, 2, W. Hanke1 and E. Arrigoni1, 3
1 Institut für Theoretische Physik und Astrophysik, Universität Würzburg am Hubland, 97074 Würzburg, Germany
2 Department of Physics, Hubei University - Wuhan 430062, PRC
3 Institut für Theoretische Physik, Computational Physics, Technische Universität Graz Petersgasse 16, A-8010 Graz, Austria
received 17 May 2005; accepted in final form 15 July 2005
published online 17 August 2005
We study numerically and partly diagrammatically the renormalization of the electron-spin interaction or vertex in a two-dimensional one-band Hubbard model with spin-fluctuation momentum transfer . We find that the renormalized electron-spin vertex decreases quite generally with decreasing temperature at all doping densities. As a combination of two concurring effects, i.e. the decrease of the vertex and the increase of the spin susceptibility, the effective pairing interaction increases with lowering temperature in the intermediate-correlation regime, but flattens off in the strong-correlation regime. Our findings indicate that in the high- cuprates the pairing mediated by antiferromagnetic spin fluctuations is substantially reduced due to vertex corrections.
71.27.+a - Strongly correlated electron systems; heavy fermions.
71.10.Fd - Lattice fermion models (Hubbard model, etc.).
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