LCAO model for 3D Fermi surface of high-T_c cuprate Tl_2Ba_2CuO_{6+delta}

TL;DR

This paper presents an analytical LCAO model for the 3D Fermi surface of Tl2Ba2CuO6+delta, highlighting the dominant role of Cu 4s orbital hopping in forming the coherent 3D Fermi surface, and proposes an experimental method to determine hopping parameters.

Contribution

The paper derives a simple analytical formula for the 3D Fermi surface of Tl2Ba2CuO6+delta within the LCAO approximation, emphasizing the importance of Cu 4s orbital hopping.

Findings

The model fits experimental data for 3D Fermi surface.

Cu 4s orbital hopping dominates in 3D Fermi surface formation.

Proposes a microstructure experiment to measure hopping parameters.

Abstract

A simple analytical formula for three-dimensional Fermi surface (3D FS) of ${\rm Tl_{2}Ba_{2}CuO_{6+\delta}}$ is derived in the framework of LCAO approximation spanned over Cu~4s, Cu~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 \tss between Cu~4s orbitals from neighbouring \cuo layers. The acceptable correspondence with the experimental data gives a hint that the \tss 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.