paper

Origin of insulating ferromagnetism in iron oxychalcogenide CeOFeSe

arXiv:2105.09239 · doi:10.1103/PhysRevLett.127.077204

Abstract

An insulating ferromagnetic (FM) phase exists in the quasi-one-dimensional iron chalcogenide CeOFeSe but its origin is unknown. To understand the FM mechanism, here a systematic investigation of this material is provided, analyzing the competition between ferromagnetic and antiferromagnetic tendencies and the interplay of hoppings, Coulomb interactions, Hund's coupling, and crystal-field splittings. Our intuitive analysis based on second-order perturbation theory shows that large entanglements between doubly-occupied and half-filled orbitals play a key role in stabilizing the FM order in CeOFeSe. In addition, via many-body computational techniques applied to a multi-orbital Hubbard model, the phase diagram confirms the proposed FM mechanism, in agreement with experiments.

6 pages, 5 figures

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