Orbital and charge ordering in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Pr</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn><mml:mi mathvariant="normal">−</mml:mi><mml:mi mathvariant="normal">x</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Ca</mml:mi></mml:mrow><mml:mrow><mml:mi mat

Анисимов, В. И.; Elfimov, Ilya; Korotin, M. A.; Terakura, Kiyoyuki

doi:10.1103/physrevb.55.15494

Cited by 70 publications

(40 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Concerning the theory, several groups have argued as to the dominant mechanism leading to the stability of the CE-type phase, but the basic picture has not been questioned [15,16,17,18,19]. However, ab initio calculations predict a noninteger mixed valence accompanying an orbitally ordered CEtype phase in half-doped manganites.…”

Section: Introductionmentioning

confidence: 99%

“…However, ab initio calculations predict a noninteger mixed valence accompanying an orbitally ordered CEtype phase in half-doped manganites. For Pr 0.5 Ca 0.5 MnO 3 , Anisimov et al [15] showed that two different Mn e g configurations exist which have almost the same charge density with different orbital configurations. The COO is predicted to be of the checkerboard type, one site having a 3x 2 − r 2 -type symmetry, the other a x 2 − y 2 -type symmetry.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Resonant x-ray diffraction of the magnetoresistant perovskitePr0.6Ca0.4MnO
Grenier
¹
,
Hill
²
,
Gibbs
³

et al. 2004
Phys. Rev. B
102
5
72
1
View full text Add to dashboard Cite

We report a resonant x-ray diffraction study of the magnetoresistant perovskite Pr0.6Ca0.4MnO3. We discuss the spectra measured above and below the semiconductor-insulator transition temperature with aid of a detailed formal analysis of the energy and polarization dependences of the structure factors and ab initio calculations of the spectra. In the low temperature insulating phase, we find that inequivalent Mn atoms order in a CE-type pattern and that the crystallographic structure of La0.5Ca0.5MnO3, (Radaelli et al., Phys. Rev. B 55, 3015 (1997)) can also describe this system in fine details. Instead, the alternative structure proposed for the so-called Zener polaron model (Daoud-Aladine et al., Phys. Rev. Lett. 89, 097205 (2002)) is ruled out by crystallographic and spectroscopic evidences. Our analysis supports a model involving orbital ordering. However, we confirm that there is no direct evidence of charge disproportionation in the Mn K-edge resonant spectra. Therefore, we consider a CE-type model in which there are two Mn sublattices, each with partial eg occupancy. One sublattice consists of Mn atoms with the 3x 2 − r 2 or 3y 2 − r 2 orbitals partially occupied in a alternating pattern, the other sublattice with the x 2 − y 2 orbital partially occupied.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Resonant x-ray diffraction of the magnetoresistant perovskitePr0.6Ca0.4MnO
Grenier
¹
,
Hill
²
,
Gibbs
³

et al. 2004
Phys. Rev. B
102
5
72
1
View full text Add to dashboard Cite

show abstract

“…We find a ground state with A-type antiferromagnetic order and an insulating gap. The gap results from a lifting of the degeneracy between the quarter-filled e g states that accompanies the in-plane orbital ordering (and driven by the large on-site repulsion [10,11]). These findings are consistent with the actual ground state of LaMnO 3 .…”

mentioning

confidence: 99%

d−dExcitations in Manganites Probed by Resonant Inelastic X-Ray Scattering

et al. 2005

View full text Add to dashboard Cite

We report the observation of temperature dependent electronic excitations in various manganites utilizing resonant inelastic x-ray scattering (RIXS) at the Mn K-edge. Excitations were observed between 1.5 and 16 eV with temperature dependence found as high as 10 eV. The change in spectral weight between 1.5 and 5 eV was found to be related to the magnetic order and independent of the conductivity. On the basis of LDA+U and Wannier function calculations, this dependence is associated with intersite d-d excitations. Finally, the connection between the RIXS cross-section and the loss function is addressed. PACS numbers: 75.47.Lx, 74.25.Jb, 71.27.+a Manganites of the form RE 1−x AE x MnO 3 where RE is a trivalent rare earth and AE a divalent alkali earth, exhibit a diverse range of magnetic and electronic phases. The recent theoretical and experimental studies have focussed on identifying the electronic ground states and the potential role of phase inhomogeneities [1,2]. However, details of the origin and nature of the electronic order remain elusive. What is known is that the various phases are stabilized through cooperative and competing interactions involving the spin, orbital, charge and electron-lattice degrees of freedom of the states derived from the Mn 3d and the O 2p bands.Current models frequently integrate out the oxygen degrees of freedom and parameterize the behavior of the Mn 3d orbitals with terms such as the hopping amplitude between neighboring Mn sites, the on-site Coulomb repulsion (U ) and the Hund's coupling (J H ), each of which are on the order of several eV. Experimental measurements of the excitation spectra up to these energies can thus play a key role in the understanding of these systems -in particular such measurements provide far more stringent tests of the various theoretical approaches than do ground state measurements. Central to such efforts will be understanding how the excitation spectrum relates to the various magnetic and electronic orderings.In this paper, we report resonant inelastic x-ray scattering studies of the electronic excitation spectrum in a number of manganites, for a range of ground states. We find that in all samples, the excitation spectra show systematic temperature dependencies associated with the magnetic ordering at energy scales up to 10 eV. The integrated spectral weight in the 1 eV to 5 eV energy range increases on entering ferromagnetic phases, decreases for antiferromagnetic spin alignment, and is unchanged through metal-insulator transitions for which the magnetic ground state is unchanged. On the basis of time-dependent density functional calculations, we argue that this temperature dependence arises from intersite d-d excitations which are suppressed or enhanced for antiferromagnetic or ferromagnetic nearest-neighbor spin correlations, respectively. These results both point to the sensitivity of RIXS to magnetic order and to the need for realistic calculations of the q-dependent dielectric function.Inelastic x-ray scattering (IXS), like optical meas...

show abstract

“…Also further-neighbour superexchange terms, that should destabilize other phases like a conventional two-sublattice antiferromagnet, might well have to be included to make the CE structure the most stable one near x = 1/2. But then one should use a multi-band model and perhaps also different values for in-plane and out-of-plane hopping amplitudes, in view of the in-plane orientation of the e (1) g orbital and orbital ordering [24,49,50]. Indeed, such models might well be required to remove the near symmetry about x = 1/2 in our phase diagram (figure 7), which is not seen in experiments.…”

Section: Discussionmentioning

confidence: 99%

Mean-field theory of charge ordering and phase transitions in the colossal-magnetoresistive manganites

Mishra

Pandit

Satpathy

1999

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

Abstract. We study phase transitions in the colossal-magnetoresistive manganites by using a mean-field theory both at zero and non-zero temperatures. Our Hamiltonian includes doubleexchange, superexchange, and Hubbard terms with on-site and nearest-neighbour Coulomb interaction, with the parameters estimated from earlier density-functional calculations. The phase diagrams show magnetic and charge-ordered (or charge-disordered) phases as a result of the competition between the double-exchange, superexchange, and Hubbard terms, the relative effects of which are sensitively dependent on parameters such as doping, bandwidth, and temperature. In accord with the experimental observations, several important features are reproduced from our model, namely, (i) a phase transition from an insulating, charge-ordered antiferromagnetic to a metallic, charge-disordered ferromagnetic state near dopant concentration x = 1/2, (ii) the reduction of the transition temperature T AF→F by the application of a magnetic field, (iii) melting of the charge order by a magnetic field, and (iv) phase coexistence for certain values of temperature and doping. An important feature, not reproduced in our model, is the antiferromagnetism in the electron-doped systems, e.g., La 1−x Ca x MnO 3 over the entire range of 0.5 x 1, and we suggest that a multi-band model which includes the unoccupied t 2g orbitals might be an important ingredient for describing this feature.

show abstract

Orbital and charge ordering inPr1−xCa

Abstract: The orbital and charge ordering in Pr 1−x Ca x MnO 3 (x=0 and 0.5) from the ab initio calculations

Cited by 70 publications

References 30 publications

Resonant x-ray diffraction of the magnetoresistant perovskitePr0.6Ca0.4MnO
Grenier
¹
,
Hill
²
,
Gibbs
³

et al. 2004
Phys. Rev. B
102
5
72
1
View full text Add to dashboard Cite

Resonant x-ray diffraction of the magnetoresistant perovskitePr0.6Ca0.4MnO
Grenier
¹
,
Hill
²
,
Gibbs
³

et al. 2004
Phys. Rev. B
102
5
72
1
View full text Add to dashboard Cite

d−dExcitations in Manganites Probed by Resonant Inelastic X-Ray Scattering

Mean-field theory of charge ordering and phase transitions in the colossal-magnetoresistive manganites

Contact Info

Product

Resources

About

Orbital and charge ordering inPr1−xCa

Abstract: The orbital and charge ordering in Pr 1−x Ca x MnO 3 (x=0 and 0.5) from the ab initio calculations

Cited by 70 publications

References 30 publications

Resonant x-ray diffraction of the magnetoresistant perovskitePr0.6Ca0.4MnOGrenier1, Hill2, Gibbs3 et al. 2004Phys. Rev. B1025721View full textAdd to dashboardCite

Resonant x-ray diffraction of the magnetoresistant perovskitePr0.6Ca0.4MnOGrenier1, Hill2, Gibbs3 et al. 2004Phys. Rev. B1025721View full textAdd to dashboardCite

d−dExcitations in Manganites Probed by Resonant Inelastic X-Ray Scattering

Mean-field theory of charge ordering and phase transitions in the colossal-magnetoresistive manganites

Contact Info

Product

Resources

About

Resonant x-ray diffraction of the magnetoresistant perovskitePr0.6Ca0.4MnO
Grenier
¹
,
Hill
²
,
Gibbs
³

et al. 2004
Phys. Rev. B
102
5
72
1
View full text Add to dashboard Cite

Resonant x-ray diffraction of the magnetoresistant perovskitePr0.6Ca0.4MnO
Grenier
¹
,
Hill
²
,
Gibbs
³

et al. 2004
Phys. Rev. B
102
5
72
1
View full text Add to dashboard Cite