Electron-doping versus hole-doping in the 2D t-t' Hubbard model

摘要

We compare the one-loop renormalization group flow to strong coupling of theelectronic interactions in the two-dimensional t-t'-Hubbard model with t'=-0.3tfor band fillings smaller and larger than half-filling. Using a numericalN-patch scheme (N=32...96) we show that in the electron-doped case withdecreasing electron density there is a rapid transition from a d(x^2-y^2)-wavesuperconducting regime with small characteristic energy scale to an approximatenesting regime with strong antiferromagnetic tendencies and higher energyscales. This contrasts with the hole-doped side discussed recently whichexhibits a broad parameter region where the renormalization group flow suggestsa truncation of the Fermi surface at the saddle points. We compare thequasiparticle scattering rates obtained from the renormalization groupcalculation which further emphasize the differences between the two cases.