Electronic structure and temperature-induced paramagnetism in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">LaCoO</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>

Saitoh, T.; Mizokawa, T.; Fujimori, A.; Abbate, M.; Takeda, Yasuo; Takano, Mikio

doi:10.1103/physrevb.55.4257

Cited by 351 publications

(320 citation statements)

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“…In addition, we check that the original Liechtenstein's rotationally invariant functional with U = 5.27 eV and J = 1.47 eV [36] gives qualitatively the same electronic structure for the HS/LS mixed states. The rationale for the U value is based on the following: (1) it is consistent with the existing photoemission and cluster calculation data (U ≈ 5~5.5 eV) [37][38][39]; (2) it produces a nonmagnetic semiconducting ground state with an energy gap of 0.7 eV, in good agreement with the experimental value of 0.6 ~ 0.9 eV [37,40]; and (3) the theoretical structure is in good agreement with experiment [41]. The ground state structure of LCO is shown in Fig.…”

Section: Computational Detailsmentioning

confidence: 97%

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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Section: Computational Detailsmentioning

confidence: 97%

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

2012

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“…A typical example is the work by Saitoh and coworkers 14 , aimed at fitting susceptibility, photoemission spectroscopy and x-ray absorption spectroscopy data and comparing the results with band structure calculations. In the midst of this activity, the behavior of the crystal structure has remained somewhat controversial.…”

Section: Hsmentioning

confidence: 99%

“…A radically different interpretation emerged from experimental studies of the electronic structure of LaCoO 3 , such as electron photo-emission spectroscopy 12 and x-ray absorption spectroscopy 13,14 . These data have been difficult to reconcile with the magnetization results, because significant changes in the spectra are only observed at the high-temperature transition.…”

Section: Hsmentioning

confidence: 99%

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Structural phenomena associated with the spin-state transition inLaCoO3

2002

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The structural properties of LaCoO 3 were studied by means of high-resolution neutron powder diffraction in the temperature range 5£T£1000 K. Changes of the Co +3 spin states in this temperature interval are shown to affect not only the unit cell volume, as previously known, but also internal parameters such as the metal-oxygen bond lengths.These data, as well as the temperature-dependent magnetic susceptibility, can be qualitatively modeled based on a 3-state (low-spin, intermediate-spin and high-spin) activated behavior, but correction terms are required for quantitative agreement. Our fits consistently indicate that the ionic radius of the intermediate-spin state (~0.56 Å) is smaller than the low-spin/high-spin average (~0.58 Å). We also present evidence of a third lattice, anomaly, occurring around 800 K, which we attribute to the formation of oxygen vacancies.

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“…All this changed with the theoretical work in 1996 by Korotin et al, who proposed on the basis of local density approximation + Hubbard U (LDA+U) band structure calculations, that the excited states are of the intermediate spin (IS, t 5 2g e 1 g , S = 1) type [13]. Since then many more studies have been carried out on LaCoO 3 with the majority of them [14,15,16,17,18,19,20,21,22,23,24,25,26,27] claiming to have proven the presence of this IS mechanism. In fact, this LDA+U work is so influential [28] that it forms the basis of most explanations for the fascinating properties of the recently synthesized layered cobaltate materials, which show giant magneto resistance as well as metal-insulator and ferroferri-antiferro-magnetic transitions with various forms of charge, orbital and spin ordering [29,30].…”

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confidence: 99%

Spin State Transition inLaCoO3Studied Using Soft X-ray Absorption Spectroscopy and Magnetic Circular Dichroism

et al. 2006

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Using soft x-ray absorption spectroscopy and magnetic circular dichroism at the Co-L2,3 edge we reveal that the spin state transition in LaCoO3 can be well described by a low-spin ground state and a triply-degenerate high-spin first excited state. From the temperature dependence of the spectral lineshapes we find that LaCoO3 at finite temperatures is an inhomogeneous mixed-spinstate system. Crucial is that the magnetic circular dichroism signal in the paramagnetic state carries a large orbital momentum. This directly shows that the currently accepted low-/intermediate-spin picture is at variance. Parameters derived from these spectroscopies fully explain existing magnetic susceptibility, electron spin resonance and inelastic neutron data.PACS numbers: 71.28.+d, 71.70.Ch, 78.70.Dm LaCoO 3 shows a gradual non-magnetic to magnetic transition with temperature, which has been interpreted originally four decades ago as a gradual population of high spin (HS, t 4 2g e 2 g , S = 2) excited states starting from a low spin (LS, t 6 2g , S = 0) ground state [1,2,3,4,5,6,7,8]. This interpretation continued to be the starting point for experiments carried out up to roughly the first half of the 1990's [9,10,11,12]. All this changed with the theoretical work in 1996 by Korotin et al., who proposed on the basis of local density approximation + Hubbard U (LDA+U) band structure calculations, that the excited states are of the intermediate spin (IS, t 5 2g e 1 g , S = 1) type [13]. Since then many more studies have been carried out on LaCoO 3 with the majority of them [14,15,16,17,18,19,20,21,22,23,24,25,26,27] claiming to have proven the presence of this IS mechanism. In fact, this LDA+U work is so influential [28] that it forms the basis of most explanations for the fascinating properties of the recently synthesized layered cobaltate materials, which show giant magneto resistance as well as metal-insulator and ferroferri-antiferro-magnetic transitions with various forms of charge, orbital and spin ordering [29,30].In this paper we critically re-examine the spin state issue in LaCoO 3 . There has been several attempts made since 1996 in order to revive the LS-HS scenario [31,32,33,34,35], but these were overwhelmed by the above mentioned flurry of studies claiming the IS mechanism [14,15,16,17,18,19,20,21,22,23,24,25,26,27]. Moreover, a new investigation using inelastic neutron scattering (INS) has recently appeared in Phys. Rev. Lett.[36] making again the claim that the spin state transition involves the IS states. Here we used soft xray absorption spectroscopy (XAS) and magnetic circular dichroism (MCD) at the Co-L 2,3 edge and we revealed that the spin state transition in LaCoO 3 can be well described by a LS ground state and a triply degenerate HS excited state, and that an inhomogeneous mixed-spinstate system is formed. Parameters derived from these spectroscopies fully explain existing magnetic susceptibility and electron spin resonance (ESR) data, and provide support for an alternative interpretation of the INS [37]. C...

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Electronic structure and temperature-induced paramagnetism inLaCoO3

Cited by 351 publications

References 46 publications

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

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

Structural phenomena associated with the spin-state transition inLaCoO3

Spin State Transition inLaCoO3Studied Using Soft X-ray Absorption Spectroscopy and Magnetic Circular Dichroism

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