Fourth Order Perturbation Theory for Normal Selfenergy in Repulsive Hubbard Model(Condensed Matter : Electronic Structure, Electrical, Magnetic and Optical Properties)

概要

論文の詳細を見る
We investigate the normal selfenergy and the mass enhancement factor in the Hubbard model on the two-dimensional square lattice. Our purpose in this paper is to evaluate the mass enhancement factor more quantitatively than the conventional third order perturbation theory. We calculate it by expanding perturbatively up to the fourth order with respect to the on-site repulsion U. We consider the cases that the system is near the half-filling, which are similar situations to high-T_c cuprates. As results of the calculations, we obtain the large mass enhancement on the Fermi surface by introducing the fourth order terms. This is mainly originated from the fourth order particle-hole and particle-particle diagrams. Although the other fourth order terms have effect of reducing the effective mass, this effect does not cancel out the former mass enhancement completely and there remains still a large mass enhancement effect. In addition, we find that the mass enhancement factor becomes large with increasing the on-site repulsion U and the density of state (DOS) at the Fermi energy p(0). According to many current reseaches, such large U and p(0) enhance the effective interaction between quasiparticles, therefore the superconducting transition temperature T_c increases. On the other hand, the large mass enhancement leads the reduction of the energy scale of quasiparticles, as a result, T_c is reduced. When we discuss T_c, wwe have to estimate these two competitive effects.
社団法人日本物理学会の論文
2005-09-15

Fourth Order Perturbation Theory for Normal Selfenergy in Repulsive Hubbard Model(Condensed Matter : Electronic Structure, Electrical, Magnetic and Optical Properties)

スポンサーリンク

概要

著者

関連論文

スポンサーリンク