Bad metal properties have motivated a description of the parent iron pnictides as correlated metals on the verge of Mott localization. What has been unclear is whether interactions can push these and related compounds to the Mott insulating side of the phase diagram. Here we consider the iron oxychalcogenides La2O2Fe2O(Se,S)2, which contain an Fe square lattice with an expanded unit cell. We show theoretically that they contain enhanced correlation effects through band narrowing compared to LaOFeAs, and we provide experimental evidence that they are Mott insulators with moderate charge gaps. We also discuss the magnetic properties in terms of a Heisenberg model with frustrating J1-J2-J2' exchange interactions on a "doubled" checkerboard lattice.
@article{arxiv.0912.4741,
title = {Band Narrowing and Mott Localization in Iron Oxychalcogenides La2O2Fe2O(Se,S)2},
author = {Jian-Xin Zhu and Rong Yu and Hangdong Wang and Liang L. Zhao and M. D. Jones and Jianhui Dai and Elihu Abrahams and E. Morosan and Minghu Fang and Qimiao Si},
journal= {arXiv preprint arXiv:0912.4741},
year = {2015}
}
Comments
4 pages, 5 eps figures. Version to appear in Phys. Rev. Lett