Numerical Study of Fermi Surface Evolution in Cuprates Using One-Band Hubbard Model

摘要

A Numerical calculation of the Fermi Surface (FS) evolution in cuprate using the one-band Hubbard model by the matrix diagonalization method has been done. This work focusses on the study of the evolution of the FS in the cuprate material, namely Bi_2Sr_2CaCu_2O_(8+δ), numerically by introducing a specific order parameter in the Hubbard model matrix. In this study, we confirm two evolution types of the FS of Bi_2Sr_2CaCu_2O_(8+δ) as an experimental result. Firstly, the evolution of the antibonding FS topology from the electron-like to the hole-like is generated by the order parameter that has a form of t_d[cos(k_x) . cos(k_y)] where t_d is the order parameter coefficient that corresponds to the hopping parameter of the atomic neighbor long-range interaction and k_x, k_y is the normalized momenta coordinate of the first Brillouin zone. On the contrary, the order parameter that has a form of t_d[cos(2k_x) + cos(2k_y)] generates the evolution of the FS from the hole-like topology to the electron-like topology. Secondly, the anisotropic evolution of the FS can be described by an extended d-wave order parameter which generating either the V-shape or U-shape type of the energy gap.