ARPES on HTSC: simplicity vs. complexity

TL;DR

This paper reviews how ARPES has clarified the electronic structure of high-temperature superconductors, revealing that their complexity can be understood as strong electron interactions within a relatively normal metallic band structure.

Contribution

The paper provides an overview of recent ARPES findings that help disentangle the complex physics of HTSC by showing their electronic structure resembles a normal metal with strong interactions.

Findings

ARPES reveals cuprates in optimal doping resemble normal metals

Electronic band structure of cuprates has been resolved

Strong electron-electron interactions are key to quasiparticle formation

Abstract

A notable role in understanding of microscopic electronic properties of high temperature superconductors (HTSC) belongs to angle resolved photoemission spectroscopy (ARPES). This technique supplies a direct window into reciprocal space of solids: the momentum-energy space where quasiparticles (the electrons dressed in clouds of interactions) dwell. Any interaction in the electronic system, e.g. superconducting pairing, leads to modification of the quasi-particle spectrum--to redistribution of the spectral weight over the momentum-energy space probed by ARPES. A continued development of the technique had an effect that the picture seen through the ARPES window became clearer and sharper until the complexity of the electronic band structure of the cuprates had been resolved. Now, in an optimal for superconductivity doping range, the cuprates much resemble a normal metal with well predicted electronic structure, though with rather strong electron-electron interaction. This principal disentanglement of the complex physics from complex structure reduced the mystery of HTSC to a tangible problem of interaction responsible for quasi-particle formation. Here we present a short overview of resent ARPES results, which, we believe, denote a way to resolve the HTSC puzzle.