Ab initio Evidence for Strong Correlation Associated with Mott Proximity in Iron-based Superconductors

TL;DR

This paper provides ab initio evidence that iron-based superconductors near a d6 configuration are close to a Mott insulator at d5, revealing strong electron correlations and complex quantum phenomena.

Contribution

It demonstrates, through variational Monte-Carlo simulations, that iron-based superconductors are near a Mott insulator, highlighting the role of Mott physics and Hund's coupling in their properties.

Findings

Proximity to Mott insulator at d5 in iron-based superconductors.

Emergence of incoherent metallic states and orbital differentiation.

Presence of antiferromagnetic quantum criticality.

Abstract

We predict that iron-based superconductors discovered near d6 configuration (5 Fe 3d orbitals filled by 6 electrons) is located on the foot of an unexpectedly large dome of correlated electron matter centered at the Mott insulator at d5 (namely, half filling). This is based on the many-variable variational Monte-Carlo results for ab initio low-energy models derived by the downfolding. The d5 Mott proximity extends to subsequent emergence of incoherent metals, orbital differentiations due to the Mott physics and Hund's-rule coupling, followed by antiferromagnetic quantum criticality, in quantitative accordance with available experiments.