Origin of Insulating Ferromagnetism in Iron Oxychalcogenide Ce<sub>2</sub>O<sub>2</sub>FeSe<sub>2</sub>
ORAL
Abstract
The mechanism of magnetic exchange in transition metal compounds continues attracting the attention of the condensed matter community. An insulating ferromagnetic (FM) phase exists in the quasi-one-dimensional iron oxychalcogenide Ce2O2FeSe2, but its origin is unknown [1]. 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 density functional theory (DFT) calculations and second-order perturbation theory show that large entanglements between doubly occupied and half-filled orbitals play a key role in stabilizing the FM order in Ce2O2FeSe2. In addition, via density matrix renormalization group (DMRG) computational techniques applied to a multiorbital Hubbard model, the phase diagram confirms the proposed FM mechanism [2].
[1] E. E.McCabe, et al., Phys. Rev. B 90, 235115 (2014).
[2] L.-F. Lin, et al., Phys. Rev. Lett. 127, 077204 (2021).
[1] E. E.McCabe, et al., Phys. Rev. B 90, 235115 (2014).
[2] L.-F. Lin, et al., Phys. Rev. Lett. 127, 077204 (2021).
*The work of L.-F. L., Y. Z., A. M., and E. D. was supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), Materials Sciences and Engineering Division. G. A. was partially supported by the Scientific Discovery through Advanced Computing (SciDAC) program funded by U.S. DOE, Office of Science, Advanced Scientific Computing Research and BES, Division of Materials Sciences and Engineering. The calculations were carried out at the University of Tennessee Advanced Computational Facility (ACF).
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Publication: L.-F. Lin, et al., Phys. Rev. Lett. 127, 077204 (2021).
Presenters
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Ling-Fang Lin
- University of Tennessee