Orbital selectivity enhanced by nematic order in FeSe

TL;DR

This paper investigates how nematic order influences orbital selectivity in FeSe, revealing that nematicity stabilizes orbital selective Mott phases and explains experimental observations of strong orbital differentiation.

Contribution

It demonstrates that nematic order enhances orbital selectivity in FeSe and proposes a mechanism involving combined bond and ferro-orbital orders to explain experimental findings.

Findings

Nematic order stabilizes orbital selective Mott phases.

Combined bond and ferro-orbital orders lead to large orbital selectivity.

Results align with experimental observations in FeSe.

Abstract

Motivated by the recent low-tempearture experiments on bulk FeSe, we study the electron correlation effects in a multiorbital model for this compound in the nematic phase using the U(1) slave-spin theory. We find that a finite nematic order helps to stabilize an orbital selective Mott phase. Moreover, we propose that when the d- and s-wave bond nematic orders are combined with the ferro-orbital order, there exists a surprisingly large orbital selectivity between the xz and yz orbitals even though the associated band splitting is relatively small. Our results explain the seemingly unusual observation of strong orbital selectivity in the nematic phase of FeSe, and uncover new clues on the nature of the nematic order, and sets the stage to elucidate the interplay between superconductivity and nematicity in iron-based superconductors.