$\alpha$-FeSe as an orbital-selective incoherent metal: An LDA+DMFT study

TL;DR

This study uses LDA+DMFT calculations to show that $ ext{α}$-FeSe exhibits an incoherent metallic state with a pseudogap due to strong multi-band correlations, supporting its proximity to Mottness and explaining its anomalous normal-state properties.

Contribution

The paper demonstrates how multi-band correlations in $ ext{α}$-FeSe lead to an incoherent metal with a pseudogap, providing a semi-quantitative explanation of its strange normal state.

Findings

Identification of a low-energy pseudogap in $ ext{α}$-FeSe.

Strong multi-band correlations induce incoherence in the normal state.

Support for $ ext{α}$-FeSe being close to Mottness.

Abstract

$\alpha$-FeSe, a prototype iron-chalcogenide superconductor, shows clear signatures of a strange incoherent normal state. Motivated thereby, we use LDA+DMFT to show how strong multi-band correlations generate a low-energy pseudogap in the normal state, giving an incoherent metal in very good semi-quantitative agreement with observations. We interpret our results in terms of $\alpha$-FeSe being close to Mottness. A wide range of anomalous responses in the "normal" state are consistently explained, lending strong support for this view. Implications for superconductivity arising from such an anomalous state are touched upon.