Magnetic properties in the Mott-insulating iron oxychalcogenides La$_{2}$O$_{2}$Fe$_{2}$OSe$_{2}$*

The role of electron correlation and magnetism in high-temperature superconductivity of the iron pnictides has been a topic of discussion. It has also motivated interest to compare related compounds with the iron pnictides and chalcogenides. Recently both electronic structure calculations and experimental measurements have indicated that the iron oxychalcogenides La$_{2}$O$_{2}$Fe$_{2}$OSe$_{2}$, which contains an Fe square lattice with an enlarged unit cell, has a larger U/t and is a Mott insulator [1]. We focus here on the understanding of the magnetism of this system. Within the density functional theory, we consider the magnetic phase diagram. Using an effective frustrating spin-exchange model in a doubled checker-board lattice, we study the magnetic excitation spectrum. Our theoretical results are compared with the emerging elastic and inelastic neutron scattering data in this compound. \\[4pt] [1] J.-X. Zhu, R. Yu \textit{et. al}, Phys. Rev. Lett. \textbf{104}, 216405 (2010).