Perturbation Study of the Conductance through an Interacting Region Connected to Multi-Mode Leads

概要

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We study the effects of electron correlation on transport through an interacting region connected to multi-mode leads based on the perturbation expansion with respect to the inter-electron interaction. At zero temperature the conductance defined in the Kubo formalism can be written in terms of a single-particle Green's function at the Fermi energy, and it can be mapped onto a transmission coefficient of the free quasiparticles described by an effective Hamiltonian. We apply this formulation to a twodimensional Hubbard model of finite size connected to two noninteracting leads. We calculate the conductance in the electron-hole symmetric case using the order U^2 self-energy. The conductance shows several maximums in the U dependence in some parameter regions of t_y/t_x, where t_x (t_y) is the hopping matrix element in the x- (y-) directions. This is caused by the resonance occurring in some of the subbands, and is related with the U dependence of the eigenvalues of the effective Hamiltonian.
社団法人日本物理学会の論文
2002-01-15