FLEX Study on Enhanced Charge Susceptibility near Antiferromagnetic Mott Transition in Two-Dimensional t-t' Hubbard Model(Condensed Matter : Electronic Structure, Electrical, Magnetic and Optical Properties)

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t is discussed on the fluctuation-exchange (FLEX) approximation that the charge susceptibility χ_c increases divergently in the 2D t-t' Hubbard model near the half-filling as the strength of the onsite Coulomb interaction U is approached to the critical value U_<cr> for the critical point to onset of the antiferromagnetic (AF) order. It turns out that the main origin of the divergence of χ_c is the Aslamazov-Larkin (AL) type contribution which can be taken into account by the FLEX approximation and is enhanced by the strong AF correlations because two AF-fluctuation modes and the vertex corretions work cooperatively to enhance χ_c. Indeed, AL-type contribution almost exhausts the enhanced part of χ_c in the region U ≃ U_<cr>. This result is consistent with experimental observations in under-doped cuprates LSCO and quantum Monte Carlo simulations by Furukawa and Imada [J. Phys. Soc. Jpn. 62 (1993) 2557].
社団法人日本物理学会の論文
2003-12-15