Correlation-corrected band topology and topological surface states in iron-based superconductors

TL;DR

This study reveals how electronic correlations in iron-based superconductors significantly influence their band topology and surface states, bringing topological features closer to the Fermi level and enabling potential quantum computing applications.

Contribution

It demonstrates that electronic correlation effects are essential for accurately predicting topological properties in iron-based superconductors, often altering their topological classification.

Findings

Electronic correlation renormalizes Fe 3d bandwidths.

Correlation shifts topological surface states closer to the Fermi level.

Correlation can induce topologically nontrivial states in some materials.

Abstract

Iron-based superconductors offer an ideal platform for studying topological superconductivity and Majorana fermions. In this paper, we carry out a comprehensive study of the band topology and topological surface states of a number of iron-based superconductors using a combination of density functional theory (DFT) and dynamical mean field theory. We find that the strong electronic correlation of Fe 3d electrons plays a crucial role in determining the band topology and topological surface states of iron-based superconductors. Electronic correlation not only strongly renormalizes the bandwidth of Fe 3d electrons, but also shifts the band positions of both Fe 3d and As/Se p electrons. As a result, electronic correlation moves the DFT-calculated topological surface states of many iron-based superconductors much closer to the Fermi level, which is crucial for realizing topological superconducting surface states and observing Majorana zero modes as well as achieving practical applications, such as quantum computation. More importantly, electronic correlation can change the band topology and make some iron-based superconductors topologically nontrivial with topological surface states whereas they have trivial band topology and no topological surface states in DFT calculations. Our paper demonstrates that it is important to take into account electronic correlation effects in order to accurately determine the band topology and topological surface states of iron-based superconductors and other strongly correlated materials.