Theoretical and experimental studies on the electronic structure of M2O3 (M = Ti, V, Cr, Mn, Fe) compounds by systematic analysis of high-energy spectroscopy

Uozumi, Takayuki; Okada, Kozo; Kotani, Akio; Zimmermann, R.; Steiner, P.; Hüfner, S.; Tezuka, Yoshihiko; Shin, Shik

doi:10.1016/s0368-2048(96)03063-0

Cited by 118 publications

(84 citation statements)

References 28 publications

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“…3 is in excellent agreement with x-ray photoemission data. 30,31 Namely, the sharp and narrow peak at low binding energies separated by a ͑pseudo͒gap from the rest of the valence band is very well reproduced. Figure 3 also shows the partial DOS decomposition into O and Cr contributions from t 2g and e g states.…”

Section: Resultsmentioning

confidence: 71%

Magnetism of chromia from first-principles calculations

2009

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The electronic structure and magnetism of chromia ͑corundum-type Cr 2 O 3 ͒ are studied using full-potential first-principles calculations. The electronic correlations are included within the LSDA+ U method. The energies of different magnetic configurations are very well fitted by the Heisenberg Hamiltonian with strong exchange interaction with two nearest neighbors and additional weak interaction up to the fifth neighbor shell. These energies are insensitive to the position of the oxygen states, indicating that magnetism in Cr 2 O 3 is dominated by direct exchange. The Néel temperature is calculated using the pair-cluster approximation for localized quantum spins of magnitude 3/2. Very good agreement with experiment is found for all properties including the equilibrium volume, spectral density, local magnetic moment, band gap, and the Néel temperature for the values of U and J that are close to those obtained within the constrained occupation method. The band gap is of the Mott-Hubbard type.

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Section: Resultsmentioning

confidence: 71%

Magnetism of chromia from first-principles calculations

2009

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“…From recent analysis of high-energy spectroscopy spectra, V 2 O 3 is not simply ascribed to the Mott-Hubbard type insulator, where the 3d orbital is the main component of the valence-band top and the conduction-band bottom, but intermediate between the Mott-Hubbard and charge-transfer type insulators, where both the valenceband top and conduction-band bottom consist of highly mixed states of the 3d and O 2p orbitals. 28,29,30) It should be emphasized that although the model we assume here does not contain the O 2p orbitals explicitly, the effects of the hybridization between the 3d and 2p orbitals can be partially included by using renormalized parameters. As will be discussed next section, the onsite effective Coulomb energy between the 3d electrons should be strongly renormalized by this d-p hybridization.…”

Section: )mentioning

confidence: 99%

Electronic Structure and Phase Transition in V₂O₃: Importance of 3d Spin-Orbit Interaction and Lattice Distortion

Tanaka

2002

J. Phys. Soc. Jpn.

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The 3d electronic structure and phase transition in pure and Cr doped V2O3 are theoretically investigated in relation to the 3d spin-orbit interaction and lattice distortion. A model consisting of the nearest-neighbor V ion pair with full degeneracy of the 3d orbitals is studied within the many-body point of view. It is shown that each V ion with S = 1 spin state has a large orbital magnetic moment ∼ 0.7µB and no orbital ordering occurs in the antiferromagnetic insulating (AFI) phase. The anomalous resonant Bragg reflection found in the AFI phase is attributed to the magnetic ordering. In the AFI and paramagnetic insulating (PI) phases, Jahn-Teller like lattice instability leads to tilting of the V ion pairs from the corundum c-axis and this causes large difference in the orbital occupation between the paramagnetic metal and the insulating phases, which is consistent with linear dichroic V 2p XAS measurements. To understand the AFI to PI transition, a model spin Hamiltonian is also proposed. The transition is found to be simultaneous order-disorder transition of the magnetic moments and tilting directions of the V ion pairs. Softening of elastic constant C44 and abrupt change in short range spin correlations observed at the transition are also explained.KEYWORDS: V 2 O 3 , electronic structure, phase transition, lattice distortion, orbital ordering, spin-orbit interaction, orbital moment, resonant x-ray scattering, V 2p XAS §1. IntroductionThe metal-insulator (Mott) transition in V 2 O 3 have been extensively studied ever since Mott suggested the possibility of the localization of electrons driven by Coulomb repulsion. 1)Above the transition temperature T N ∼ 155K, the material is paramagnetic metal (PM) and has the corundum structure with the trigonal symmetry (space group R3c). Below T N , it is an antiferromagnetic insulator (AFI) and the lattice distortion to the monoclinic structure (I2/a) takes place.2) Cr doped alloys (V 1−x Cr x ) 2 O 3 exhibit also interesting features. For 0.005 < x < 0.018, at a temperature above the AFI → PM transition, the material further undergoes a PM to paramagnetic insulator (PI) phase transition with no change in the crystal structure. For much higher Cr concentration x > 0.018, the PM phase disappears and a AFI → PI transition takes place.Although V 2 O 3 and its alloys are often referred to a typical example of the Mott-Hubbard system, there are experimental facts showing the complex aspects of these materials, which can not be explained by the simple single-band Hubbard model. In the AFI phase, they exhibit unusual magnetic order, which breaks corundum trigonal symmetry.8) Neutron scattering experiments have been performed by Bao et al. and abrupt change in spatial spin correlation functions has been reported both at the AFI → PM and the AFI → PI transitions. 9, 10)This switching of spin correlation indicates that the phase transitions can not be considered as usual order-disorder magnetic transition. Softening of the C 44 elastic constant has been observed in ultrasonic wa...

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“…By contrast photoemission studies 5 and inverse photoemission experiments 6 suggested that α−FeCrO 3 adopted an ilmenite-like R 3 structure. For x = 0.8, 1.0 and 1.2 powder neutron diffraction lines are consistent with the spin ordering of α-Fe 2 O 3 8 .…”

Section: Introductionmentioning

confidence: 99%

First-principles study of the mixed oxideα−FeCrO3

Moore

2007

Phys. Rev. B

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Theoretical and experimental studies on the electronic structure of M2O3 (M = Ti, V, Cr, Mn, Fe) compounds by systematic analysis of high-energy spectroscopy

Cited by 118 publications

References 28 publications

Magnetism of chromia from first-principles calculations

Magnetism of chromia from first-principles calculations

Electronic Structure and Phase Transition in V₂O₃: Importance of 3d Spin-Orbit Interaction and Lattice Distortion

First-principles study of the mixed oxideα−FeCrO3

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Theoretical and experimental studies on the electronic structure of M2O3 (M = Ti, V, Cr, Mn, Fe) compounds by systematic analysis of high-energy spectroscopy

Cited by 118 publications

References 28 publications

Magnetism of chromia from first-principles calculations

Magnetism of chromia from first-principles calculations

Electronic Structure and Phase Transition in V2O3: Importance of 3d Spin-Orbit Interaction and Lattice Distortion

First-principles study of the mixed oxideα−FeCrO3

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Electronic Structure and Phase Transition in V₂O₃: Importance of 3d Spin-Orbit Interaction and Lattice Distortion