Contribution from optically excited many-electron states to the superexchange interaction in Mott-Hubbard insulators

Гавричков, В. А.; Polukeev, S. I.; Овчинников, С. Г.

doi:10.1103/physrevb.95.144424

Cited by 28 publications

(27 citation statements)

References 44 publications

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“…Eliminating the oxygen states one can obtain the effective Hubbard model with cation-cation hopping t ∼ t 2 pd (ε p − ε d ) and then the effective Heisenberg model may be obtained by the unitary transformation of this Hubbard model 25,26 with the superexchange interaction of the kinematic origin J ∼ t 2 U . In the paper we generalize previous results for the superexchange interaction in FeBO 3 iron borate under high pressure and optical pumping 5,19 to the different transition metals oxides with magnetic ions in the d 2 -d 8 configurations. The electronic structure of 3d transition metal oxides is characterized by a set of narrow Hubbard bands, and the superexchange interaction appears in a second order perturbation theory over interband hopping from the occupied low Hubbard band into the empty upper Hubbard band and back.…”

Section: Introductionsupporting

confidence: 75%

Cation spin and superexchange interaction in oxide materials below and above spin crossover under high pressure

2020

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We derived simple rules for the sign of superexchange interaction based on the multielectron calculations of the superexchange interaction in the transition metal oxides that are valid both below and above spin crossover under high pressure. The superexchange interaction between two cations in d n configurations is given by a sum of individual contributions related to the electron-hole virtual excitations to the different states of the d n+1 and d n−1 configurations. Using these rules, we have analyzed the sign of the superexchange interaction of a number of oxides with magnetic cations in electron configurations from d 2 till d 8 : the iron, cobalt, chromium, nickel, copper and manganese oxides with increasing pressure. The most interesting result concerns the magnetic state of cobalt and nickel oxides CoO, Ni2O3 and also La2CoO4, LaNiO3 isostructural to well-known high-TC and colossal magnetoresistance materials. These oxides have a spin 1 2 at the high pressure. Change of the interaction from antiferromagnetic below spin crossover to ferromagnetic above spin crossover is predicted for oxide materials with cations in d 5 (FeBO3) and d 7 (CoO) configurations, while for materials with the other d n configurations spin crossover under high pressure does not change the sign of the superexchange interaction.

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Section: Introductionsupporting

confidence: 75%

Cation spin and superexchange interaction in oxide materials below and above spin crossover under high pressure

2020

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“…Under optical pumping, the 2 4 T triplet excited states with spin 3 2 S  are populated. The conclusion of the multi-electron approach [43] is that the resonant occupation of some excited states of the Fe 3+ ions under optical pumping may change the value and even the sign of the superexchange interaction between the excited ion and a neighboring ion in the ground state. For the 4 T2 excited term of the Fe 3+ ion a ferromagnetic (FM) type of exchange has been found [45].…”

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confidence: 99%

Resonant Pumping of d−d Crystal Field Electronic Transitions as a Mechanism of Ultrafast Optical Control of the Exchange Interactions in Iron Oxides

Mikhaylovskiy

Huisman²,

Гавричков

et al. 2020

Phys. Rev. Lett.

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“…To obtain the interatomic exchange interaction we apply the method developed for the Hubbard model [35] and generalized for arbitrary set of local eigenstates in [24]. The idea is to construct the effective Hamiltonian excluding the interband interatomic hopping.…”

Section: Two-band Kanamori Modelmentioning

confidence: 99%

Magnetism in spin crossover systems: Short-range order and effects beyond the Heisenberg model

et al. 2019

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To study non-Heisenberg effects in the vicinity of spin crossover in strongly correlated electron systems we derive an effective low-energy Hamiltonian for the two-band Kanamori model. It contains Heisenberg high-spin term proportional to exchange constant as well as low-spin term proportional to spin gap parameter εs. Using cluster mean field theory we obtain several non-Heisenberg effects. Near critical value of spin gap ε c s there is a magnetic phase transition of first order. In the vicinity of ε c s in the paramagnetic phase we observe non trivial behavior of the Curie constant in the paramagnetic susceptibility in the wide range of temperature. Reentrant temperature behavior of nearest-neighbor spin-spin correlations is observed at εs > ε c s . Finally, pressure-temperature magnetic phase diagram for ferroperriclase is obtained using the effective Hamiltonian.

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Contribution from optically excited many-electron states to the superexchange interaction in Mott-Hubbard insulators

Cited by 28 publications

References 44 publications

Cation spin and superexchange interaction in oxide materials below and above spin crossover under high pressure

Cation spin and superexchange interaction in oxide materials below and above spin crossover under high pressure

Resonant Pumping of d−d Crystal Field Electronic Transitions as a Mechanism of Ultrafast Optical Control of the Exchange Interactions in Iron Oxides

Magnetism in spin crossover systems: Short-range order and effects beyond the Heisenberg model

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