LCAO model for 3D Fermi surface of high-T_c cuprate Tl₂Ba₂CuO_6+δ

Abstract

A simple analytical formula for three-dimensional Fermi surface (3D FS) of ${\rm Tl}_2{\rm Ba}_2{\rm CuO}_{6+\delta}$ is derived in the framework of LCAO approximation spanned over Cu 4s, Cu 3d$3d_{x^2 - y^2 }$, O 2p_x and O 2p_y states. This analytical result can be used for fitting of experimental data for 3D FS such as polar angle magnetoresistance oscillation. The model takes into account effective copper-copper hopping amplitude t_ss between Cu 4s orbitals from neighbouring ${\textrm{CuO}_2}$ layers. The acceptable correspondence with the experimental data gives a hint that the t_ss amplitude dominates in formation of coherent 3D FS, and other oxygen-oxygen and copper-oxygen amplitudes are rather negligible. For absolute determination of the hopping parameters a simple electronic experiment with a field effect transistor type microstructure is suggested. The thin superconductor layer is the source-drain channel of the layered structure where an AC current is applied.