Exchange coupling in transition metal monoxides: Electronic structure calculations

Fischer, Guntram; Däne, M.; Ernst, A.; Bruno, P.; Lüders, M.; Szotek, Z.; Temmerman, W. M.; Hergert, W.

doi:10.1103/physrevb.80.014408

Cited by 125 publications

(141 citation statements)

References 65 publications

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“…exchange parameters in the 1:1 HS/LS state [29,30]. The qualitative feature of the exchange parameters is further verified within a model superexchange calculation.…”

Section: Introductionmentioning

confidence: 90%

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Strain-driven spin-state transition and superexchange interaction in LaCoO3:Abinitiostudy

2012

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Using spin density functional theory with the Hubbard correction we investigate the magnetic structure of strained LaCoO 3 . We show that beyond biaxial tensile strain of 2.5%, local magnetic moments originating from the high spin (HS) state of Co 3+ emerge in a low spin (LS) Co 3+ matrix. In contrast, we find that compressive strain is not able to stabilize a magnetic state due to geometric constraints. LaCoO 3 accommodates tensile strain via spin state disproportionation resulting in an unusual sublattice structure. In tensile-strained LaCoO 3 , the first nearest neighbor (n.n.) exchange coupling is ferromagnetic (FM) while the second n.n. interaction is stronger and antiferromagnetic (AFM). This unusual feature of the exchange parameters is qualitatively verified with a model superexchange calculation. Due to the competition between the FM and AFM couplings in the system, we find that the most probable magnetic structure of tensile-strained LCO is a canted-spin structure, which may explain the relatively small observed magnetic moment of 0.7μ B /Co 3+ .

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“…exchange parameters in the 1:1 HS/LS state [29,30]. The qualitative feature of the exchange parameters is further verified within a model superexchange calculation.…”

Section: Introductionmentioning

confidence: 90%

“…Therefore, to map the exchange coupling between the local moments, we use an effective Heisenberg Hamiltonian for the exchange energy of the system [29,30]:…”

Section: Superexchange Interaction In the 1:1 Hs/ls Mixed Statementioning

confidence: 99%

Strain-driven spin-state transition and superexchange interaction in LaCoO3:Abinitiostudy

2012

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“…A common difference among ab initio theories is the first-and second-nearest-neighbor exchange parameter ratio J 1 =J 2 , which can vary widely from more than 3.5 to less than 0.4 (see, e.g., Table III in Ref. [6]). The present DLM-DFT method, producing essentially Anderson superexchange, predicts J 1 =J 2 ¼ 0.502.…”

Section: Fig 1 Combined Atomic and Magnetic Pdfs Of Mno Atmentioning

confidence: 99%

“…For example, various tight-binding models [2][3][4] and many important implementations of density functional theory (DFT) [5][6][7][8][9][10] that include the effects of strong electron correlations have been tested against MnO. Modern applications of these ab initio methods can successfully determine gross features of MnO, including the average atomic structure, magnetic ordering temperature, and local magnetic moment size.…”

mentioning

confidence: 99%

Verification of Anderson Superexchange in MnO via Magnetic Pair Distribution Function Analysis andab initioTheory

et al. 2016

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We present a temperature-dependent atomic and magnetic pair distribution function (PDF) analysis of neutron total scattering measurements of antiferromagnetic MnO, an archetypal strongly correlated transition-metal oxide. The known antiferromagnetic ground-state structure fits the low-temperature data closely with refined parameters that agree with conventional techniques, confirming the reliability of the newly developed magnetic PDF method. The measurements performed in the paramagnetic phase reveal significant short-range magnetic correlations on a ∼1 nm length scale that differ substantially from the lowtemperature long-range spin arrangement. Ab initio calculations using a self-interaction-corrected local spin density approximation of density functional theory predict magnetic interactions dominated by Anderson superexchange and reproduce the measured short-range magnetic correlations to a high degree of accuracy. Further calculations simulating an additional contribution from a direct exchange interaction show much worse agreement with the data. The Anderson superexchange model for MnO is thus verified by experimentation and confirmed by ab initio theory.

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“…The simple rock-salt structure along with the inability of regular DFT functionals to correctly describe these materials, make NiO and MnO typical benchmark systems to test methods for the calculation of exchange interactions in strongly correlated systems. Beyond the DFT methods such as LDA+U, [34,44,45] hybrid functionals, [46,47] the self-interaction correction, [41,48] GW approximation [49] and dynamical mean-field theory [42,50] have been used successfully to improve the correspondence between calculations and experiments in these materials. [34,42,46,47] In contrast, LSIC overestimates the electron localization, leading to a slight underestimation of the exchange interactions.…”

Section: Niomentioning

confidence: 99%

Exchange interactions in transition metal oxides: the role of oxygen spin polarization

Logemann¹,

Руденко²,

Katsnelson³

et al. 2017

J. Phys.: Condens. Matter

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Abstract. Magnetism of transition metal (TM) oxides is usually described in terms of the Heisenberg model, with orientation-independent interactions between the spins. However, the applicability of such a model is not fully justified for TM oxides because spin polarization of oxygen is usually ignored. In the conventional model based on the Anderson principle, oxygen effects are considered as a property of the TM ion and only TM interactions are relevant. Here, we perform a systematic comparison between two approaches for spin polarization on oxygen in typical TM oxides. To this end, we calculate the exchange interactions in NiO, MnO, and hematite (Fe 2 O 3 ) for different magnetic configurations using the magnetic force theorem. We consider the full spin Hamiltonian including oxygen sites, and also derive an effective model where the spin polarization on oxygen renormalizes the exchange interactions between TM sites. Surprisingly, the exchange interactions in NiO depend on the magnetic state if spin polarization on oxygen is neglected, resulting in non-Heisenberg behavior. In contrast, the inclusion of spin polarization in NiO makes the Heisenberg model more applicable. Just the opposite, MnO behaves as a Heisenberg magnet when oxygen spin polarization is neglected, but shows strong non-Heisenberg effects when spin polarization on oxygen is included. In hematite, both models result in non-Heisenberg behavior. General applicability of the magnetic force theorem as well as the Heisenberg model to TM oxides is discussed.

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Exchange coupling in transition metal monoxides: Electronic structure calculations

Cited by 125 publications

References 65 publications

Strain-driven spin-state transition and superexchange interaction in LaCoO3:Abinitiostudy

Strain-driven spin-state transition and superexchange interaction in LaCoO3:Abinitiostudy

Verification of Anderson Superexchange in MnO via Magnetic Pair Distribution Function Analysis andab initioTheory

Exchange interactions in transition metal oxides: the role of oxygen spin polarization

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