Electronic structure of the high-temperature oxide superconductors

TLDR

High‑temperature cuprate superconductors have seen critical temperatures rise from 30 K to over 125 K, prompting extensive electronic‑structure calculations, yet the antiferromagnetic regions of their phase diagrams remain a major theoretical challenge. This review compiles density‑functional electronic‑structure calculations and compares their outcomes with experimental observations. The review covers density‑functional calculations, structural stability, lattice dynamics, electron‑phonon coupling, and efforts to determine interaction constants for model Hamiltonian treatments of many‑body effects. The electronic states are dominated by strongly hybridized copper d and oxygen p orbitals, and spectroscopic data show that while density‑functional calculations capture many features, self‑energy corrections are essential for a detailed description.

Abstract

Since the discovery of superconductivity above 30 K by Bednorz and M\"uller in the La copper oxide system, the critical temperature has been raised to 90 K in Y${\mathrm{Ba}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7}$ and to 110 and 125 K in Bi-based and Tl-based copper oxides, respectively. In the two years since this Nobel-prize-winning discovery, a large number of electronic structure calculations have been carried out as a first step in understanding the electronic properties of these materials. In this paper these calculations (mostly of the density-functional type) are gathered and reviewed, and their results are compared with the relevant experimental data. The picture that emerges is one in which the important electronic states are dominated by the copper $d$ and oxygen $p$ orbitals, with strong hybridization between them. Photon, electron, and positron spectroscopies provide important information about the electronic states, and comparison with electronic structure calculations indicates that, while many features can be interpreted in terms of existing calculations, self-energy corrections ("correlations") are important for a more detailed understanding. The antiferromagnetism that occurs in some regions of the phase diagram poses a particularly challenging problem for any detailed theory. The study of structural stability, lattice dynamics, and electron-phonon coupling in the copper oxides is also discussed. Finally, a brief review is given of the attempts so far to identify interaction constants appropriate for a model Hamiltonian treatment of many-body interactions in these materials.