Doping-Induced Alterations in Electronic Structure of Copper Oxide Superconductors and a New Horizon for Higher Tc materials

TL;DR

This paper develops a non-rigid band theory to explain doping-induced changes in the electronic structure of cuprate superconductors, revealing the role of Fermi pockets and arcs in pseudogap phenomena and superconductivity, and proposing pathways for higher Tc materials.

Contribution

It introduces a novel non-rigid band theory that accounts for doping-induced structural and electronic changes in copper oxide superconductors, linking Fermi surface features to superconductivity.

Findings

Fermi pockets and arcs characterize the underdoped cuprates' Fermi surface.

The pseudogap is related to the existence of Fermi pockets.

Carriers on Fermi pockets contribute to d-wave superconductivity.

Abstract

By paying special attention to the fact that the doped holes induce deformation of CuO6 octahedrons (or CuO5 pyramids) in cuprate superconductors, we develop a non-rigid band theory treating doping-induced alterations of energy-band structures in copper oxide superconductors. Thanks to this theory, we obtain a complete picture of the doping-induced alteration in the electronic structure of La2CuO4, from the spin-disordered insulating phase to the metallic phase. We conclude that the Fermi surface structure of this cuprate in the underdoped region consists of Fermi pockets in the antinodal region and Fermi arcs in the nodal region, and thus that the origin of a so-called pseudogap is closely related to the existence of Fermi pockets. Moreover, we show that the carriers on the Fermi pockets contribute to the phonon mechanism in d-wave superconductivity. Finally, we discuss how one will be able to find higher Tc materials, based on the conclusions mentioned above.