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Fang, Zhong; Nagaosa, Naoto

doi:10.1103/physrevlett.93.176404

Cited by 74 publications

(70 citation statements)

References 37 publications

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“…In this sense, our strategy is completely different from conventional LDA+U calculations, where the on-site Coulomb interaction U is typically treated as an adjustable parameter (e.g., Refs. 27,29,31,32,33). By changing U , one can certainly get a better numerical agreement with some experimental data already at the HF level.…”

Section: Introductionsupporting

confidence: 54%

“…The order of the magnetic states, corresponding to the increase of the total energy, is G→C→flip→A→F, which is well consistent with results of all-electron LDA+U calculations. 27,29,54 However, the orbital ordering is not fully quenched by the crystal distortion and to certain extent can adjust the change of the magnetic state through the Kugel-Khomskii mechanism. 51 This is seen particularly well in the behavior of interatomic magnetic interactions, which reveal an appreciable dependence on the magnetic state.…”

Section: Low-temperature Orthorhombic Phase (T < 77 K)mentioning

confidence: 99%

“…19,20,21,22,23,24) as well as the first-principles electronic structure calculations (Refs. 25,26,27,28,29,30,31,32,33). The problem is still far from being understood, and remains to be the subject of numerous contradictions and debates.…”

Section: Introductionmentioning

confidence: 99%

“…For example, at the HF level, using relatively simple model Hamiltonian, which is limited exclusively by the t 2g bands, we will be able to reproduce the main results of all-electron calculations. 27,29 Furthermore, due to the simplicity of the model Hamiltonian we can easily go beyond the HF approximation and include the correlation effects.…”

Section: Introductionmentioning

confidence: 99%

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Lattice distortion and magnetism of3d−t2gperovskite oxides

Solovyev

2006

Phys. Rev. B

150

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Several puzzling aspects of interplay of the experimental lattice distortion and the the magnetic properties of four narrow t2g-band perovskite oxides (YTiO3, LaTiO3, YVO3, and LaVO3) are clarified using results of first-principles electronic structure calculations. First, we derive parameters of the effective Hubbard-type Hamiltonian for the isolated t2g bands using newly developed downfolding method for the kinetic-energy part and a hybrid approach, based on the combination of the random-phase approximation and the constraint local-density approximation, for the screened Coulomb interaction part. Apart form the above-mentioned approximation, the procedure of constructing the model Hamiltonian is totally parameter-free. The results are discussed in terms of the Wannier functions localized around transition-metal sites. The obtained Hamiltonian was solved using a number of techniques, including the mean-field Hartree-Fock (HF) approximation, the second-order perturbation theory for the correlation energy, and a variational superexchange theory, which takes into account the multiplet structure of the atomic states. We argue that the crystal distortion has a profound effect not only on the values of the crystal-field (CF) splitting, but also on the behavior of transfer integrals and even the screened Coulomb interactions. Even though the CF splitting is not particularly large to quench the orbital degrees of freedom, the crystal distortion imposes a severe constraint on the form of the possible orbital states, which favor the formation of the experimentally observed magnetic structures in YTiO3, YVO3, and LaVO3 even at the level of mean-field HF approximation. It is remarkable that for all three compounds, the main results of all-electron calculations can be successfully reproduced in our minimal model derived for the isolated t2g bands. We confirm that such an agreement is only possible when the nonsphericity of the Madelung potential is explicitly included into the model. Beyond the HF approximation, the correlations effects systematically improve the agreement with the experimental data. Using the same type of approximations we could not reproduce the correct magnetic ground state of LaTiO3. However, we expect that the situation may change by systematically improving the level of approximations for dealing with the correlation effects.

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Section: Introductionsupporting

confidence: 54%

Section: Low-temperature Orthorhombic Phase (T < 77 K)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Lattice distortion and magnetism of3d−t2gperovskite oxides

Solovyev

2006

Phys. Rev. B

150

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“…The insulating Y 1−x La x VO 3 , a JT active system, has been of considerable interest due to its complex phase diagram [5][6][7][8][9][10][11][12][13] associated with orbital physics [14][15][16][17][18][20][21][22]. With cooling, the parent compound, YVO 3 , undergoes a transition to a G-type orbital ordering (anti-phase ordering along the c-axis, G-OO) at T OO ∼ 200 K, followed by a C -type antiferromagnetic spin ordering at T N ∼ 116 K (C-SO) and finally to an orbital flipping transition at T CG ∼ 77 K with C -type orbital ordering (in-phase ordering along the c-axis, C-OO) and G-type spin ordering (G-SO) [19,20].…”

Section: Introductionmentioning

confidence: 99%

Y1−xLaxVO3: Effects of doping on orbital ordering

et al. 2014

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The effects of isovalent doping on orbital ordering in the perovskite Y1−xLaxVO3 was investigated using neutron diffraction and the pair distribution function analysis. YVO3 is a prototype for orbital ordering, exhibiting two consecutive transitions to G-type and C-type ordering with decreasing temperature. Evidence for local orbital ordering above the transition temperature of TOO ∼ 200 K is presented, obtained from the temperature dependence of the oxygen-oxygen octahedral correlations. This suggests that locally, G-type orbital ordering is present above the TOO temperature but it is short-range. With doping, it is expected that orbital ordering disappears altogether. By 30 % of doping as in Y0.7La0.3VO3, even though no orbital ordering is expected, we find that locally, C-type orbital correlations are most likely present below the magnetic transition temperature, TN , allowing for a direct paramagnetic to orbitally ordered/antiferromagnetic transition in this composition.

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Electronic Reconstruction in (LaVO₃)_m/SrVO₃ (_m = 5, 6) Superlattices

Dai

Lüders

Frésard

et al. 2018

Adv Materials Inter

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ferromagnetic (AFM) to a paramagnetic state. [13] In contrast, bulk SrVO 3 is a paramagnetic metal with cubic symmetry. [14] The electronic configurations of the V ions in LaVO 3 and SrVO 3 , respectively, are 3d 2 (V 3+ ) and 3d 1 (V 4+ ). It has been found that the solid solution La 1-x Sr x VO 3 , containing mixed V 3+ and V 4+ states, shows a non-Fermi liquid behavior up to very high temperatures and is subject to an insulator-to-metal transition under hole doping. [15,16] Appearance of both V 3+ and V 4+ states at the interfaces of (LaVO 3 ) 6 /(SrVO 3 ) 3 superlattices has been reported in ref.[10] without identifying a specific spatial pattern. In addition, it is known that the magnetization in (LaVO 3 ) m /SrVO 3 superlattices depends on the thickness of the LaVO 3 layer, with m = 4, 6 yielding larger saturation magnetization than m = 3, 5. [6] The fact that in the latter case the saturation magnetization does not exceed the threshold of the substrate impurities indicates that there is no macroscopic magnetization. The mechanism responsible for the deviating behaviors of superlattices with odd and even thicknesses is not fully understood so far. While it could be a pure strong correlation effect, [17] results on the bulk compounds indicate that strain introduced into the superlattices by the substrate may also influence the magnetic behavior (as well as other physical properties). [18] Distortions in vanadate superlattices generated by charge disproportionation into V 3+ and V 4+ ions have the potential to result in ferroelectricity [19] and distortions of the VO 6 octahedra can have complex effects on the orbital occupations. [20] Based on these considerations, we will study in the present work (LaVO 3 ) m /SrVO 3 superlattices by numerical calculations within density functional theory, using experimental lattice parameters. Our considerations will focus on the cases m = 5 and 6, as examples for superlattices with odd and even thicknesses. We will establish the magnetic ground state, provide detailed insight into the electronic reconstruction (in particular with respect to the V ions at the interfaces of the superlattices), and explain the observed m-dependence of the electronic and magnetic properties. MethodologySpin-polarized first-principles calculations are performed employing the projector augmented wave method of the Vienna The (LaV 3+ O 3 ) m /SrV 4+ O 3 (m = 5, 6) superlattices are investigated by first principles calculations. While bulk LaVO 3 is a C-type antiferromagnetic semiconductor and bulk SrVO 3 is a paramagnetic metal, semiconducting A-type antiferromagnetic states for both superlattices are found due to epitaxial strain. At the interfaces, however, the V spins couple antiferromagnetically for m = 5 and ferromagnetically for m = 6 (m-dependence of the magnetization). Electronic reconstruction in form of charge ordering is predicted to occur with V 3+ and V 4+ states arranged in a checkerboard pattern on both sides of the SrO layer. As compared to bulk LaVO 3 , the presence of V 4+ ions...

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Quantum Versus Jahn-Teller Orbital Physics inYVO3andLa

Cited by 74 publications

References 37 publications

Lattice distortion and magnetism of3d−t2gperovskite oxides

Lattice distortion and magnetism of3d−t2gperovskite oxides

Y1−xLaxVO3: Effects of doping on orbital ordering

Electronic Reconstruction in (LaVO₃)_m/SrVO₃ (_m = 5, 6) Superlattices

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Quantum Versus Jahn-Teller Orbital Physics inYVO3andLa

Cited by 74 publications

References 37 publications

Lattice distortion and magnetism of3d−t2gperovskite oxides

Lattice distortion and magnetism of3d−t2gperovskite oxides

Y1−xLaxVO3: Effects of doping on orbital ordering

Electronic Reconstruction in (LaVO3)m/SrVO3 (m = 5, 6) Superlattices

Contact Info

Product

Resources

About

Electronic Reconstruction in (LaVO₃)_m/SrVO₃ (_m = 5, 6) Superlattices