Orbital selective Fermi surface shifts and mechanism of high T$_c$ superconductivity in correlated AFeAs (A=Li,Na)

TL;DR

This study uses DMFT and ARPES to explore the mechanisms behind high-temperature superconductivity in LiFeAs, emphasizing the importance of orbital-dependent correlations and Fermi surface shifts in mediating superconductivity.

Contribution

It demonstrates that orbital-dependent correlation effects suppress Fermi surface nesting in LiFeAs, which is essential for spin-fluctuation mediated superconductivity, contrasting with NaFeAs.

Findings

Fermi surface nesting is suppressed in LiFeAs due to correlations.

Good Fermi surface nesting in NaFeAs leads to spin density wave.

Charge self-consistent correlation effects are crucial for understanding FS instabilities.

Abstract

Based on the dynamical mean field theory (DMFT) and angle resolved photoemission spectroscopy (ARPES), we have investigated the mechanism of high $T_c$ superconductivity in stoichiometric LiFeAs. The calculated spectrum is in excellent agreement with the observed ARPES measurement. The Fermi surface (FS) nesting, which is predicted in the conventional density functional theory method, is suppressed due to the orbital-dependent correlation effect with the DMFT method. We have shown that such marginal breakdown of the FS nesting is an essential condition to the spin-fluctuation mediated superconductivity, while the good FS nesting in NaFeAs induces a spin density wave ground state. Our results indicate that fully charge self-consistent description of the correlation effect is crucial in the description of the FS nesting-driven instabilities.