An ARPES view on the high-Tc problem: phonons vs spin-fluctuations

TL;DR

This paper reviews ARPES experiments to understand high-Tc superconductivity, highlighting the roles of spin fluctuations in cuprates and phonons in pnictides, proposing different mechanisms for these materials.

Contribution

It offers a unified view of electronic interactions in high-Tc materials, emphasizing spin fluctuations in cuprates and phonons in pnictides as key mediators.

Findings

Spin fluctuations explain the pseudogap and high Tc in cuprates.

Strong electron-phonon coupling is significant in pnictides.

Pseudogap arises from a density wave instability.

Abstract

We review the search for a mediator of high-Tc superconductivity focusing on ARPES experiment. In case of HTSC cuprates, we summarize and discuss a consistent view of electronic interactions that provides natural explanation of both the origin of the pseudogap state and the mechanism for high temperature superconductivity. Within this scenario, the spin-fluctuations play a decisive role in formation of the fermionic excitation spectrum in the normal state and are sufficient to explain the high transition temperatures to the superconducting state while the pseudogap phenomenon is a consequence of a Peierls-type intrinsic instability of electronic system to formation of an incommensurate density wave. On the other hand, a similar analysis being applied to the iron pnictides reveals especially strong electron-phonon coupling that suggests important role of phonons for high-Tc superconductivity in pnictides.