# Coexistence of localized and itinerant magnetism in intercalated iron-selenide (Li,Fe)OHFeSe

## TL;DR

This study theoretically investigates the electronic structure and magnetism of (Li,Fe)OHFeSe, revealing coexistence of localized and itinerant magnetism, electron doping effects, and interlayer magnetic coupling that influence superconductivity.

## Contribution

It provides a detailed theoretical analysis of the magnetic and electronic properties of intercalated FeSe, highlighting the coexistence of localized and itinerant magnetism and the role of the spacer layer.

## Key findings

- Fe in (Li,Fe)OH layer is Fe2+ with electron doping to FeSe
- FeSe layer is a striped antiferromagnetic metal
- (Li,Fe)OH layer exhibits weak localized magnetism and ferromagnetic coupling

## Abstract

The electronic structure and magnetism of a new magnetic intercalation compound (Li0.8Fe0.2)OHFeSe are investigated theoretically. The electronic structure calculations predict that the Fe in the (Li,Fe)OH intercalated layer is in +2 valence state, i.e. there is electron doping to the FeSe layer, resulting in the shrinking of the Fermi surface (FS) pocket around Gamma and a strong suppression of dynamical spin susceptibility at M in comparison with the bulk FeSe compound. The ground state of the FeSe layer is a striped antiferromagnetic (SAFM) metal, while the (Li,Fe)OH layer displays a very weak localized magnetism, with an interlayer ferromagnetic (FM) coupling between the FeSe and intercalated (Li,Fe)OH layers. Moreover, the (Li,Fe)OH is more than a block layer; it is responsible for enhancing the antiferromagnetic (AFM) correlation in the FeSe layer through interlayer magnetic coupling. We propose that the magnetic spacer layer introduces a tuning mechanism for spin fluctuations associated with superconductivity in iron-based superconductors.