Physical review. B, Condensed matter
Magnetic susceptibility and the Landau Fermi-liquid parameter of the Hubbard model and the three-band CuO2 model
Hiroyuki Kaga, Taiichirou Saikawa, Chihiro Ohmori
Abstract
Magnetic susceptibilities of interacting (d) electrons in the Hubbard model and the three-band ${\mathrm{CuO}}_{2}$ model are worked out within the Gaussian fluctuations of the functional integral in the slave boson representation. The normalized Landau Fermi-liquid parameter |${\mathit{F}}_{0}^{\mathit{a}}$|/\ensuremath{\alpha} (\ensuremath{\alpha}\ensuremath{\equiv}${\mathit{W}}_{0}$${\mathit{N}}_{\mathit{F}}^{0}$, ${\mathit{N}}_{\mathit{F}}^{0}$ the density of states at the Fermi level, and ${\mathit{W}}_{0}$ the bare bandwidth) defined from the susceptibility expression is investigated for the two models as functions of Coulomb repulsion U, charge-transfer energy \ensuremath{\Delta}, and doping concentration \ensuremath{\delta}. It is shown that the Landau parameter for the three-band model is larger and exhibits different renormalization behaviors than that for the Hubbard model in both the weak- and strong-coupling regimes except in the Mott-Hubbard weak-coupling regime, where it takes the same random-phase approximation form U/${\mathit{W}}_{0}$ as the latter. The reasons for these results are analyzed. The slave-boson Landau parameter for the Hubbard model exactly reproduces the T-matrix expression |${\mathit{F}}_{0}^{\mathit{a}}$|/\ensuremath{\alpha}=U/${\mathit{W}}_{0}$/(1+U/${\mathit{W}}_{0}$) in the low-density limit, whose renormalization has the different origin from that in the dilutely doped regime. \textcopyright{} 1996 The American Physical Society.