Evidence for Electronic Phase Separation between Orbital Orderings in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>SmVO</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:math>

Sage, M. H.; Blake, Graeme R.; Nieuwenhuys, G. J.; Palstra, Thomas

doi:10.1103/physrevlett.96.036401

Cited by 47 publications

(84 citation statements)

References 20 publications

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“…[100] in order to satisfy the experimental constraint that the C-AF and G-AO order appear almost simultaneously in LaVO 3 [93]. The experimental value T exp N1 = 143 K for LaVO 3 [93] was fairly well reproduced in the present model taking J = 200 K. The functional dependence of the remaining two parameters {E z (ϑ), V ab (ϑ)} on the tilting angle ϑ was derived from the point charge model [100] using the structural data for the RVO 3 series [103,104] …”

Section: Phase Diagram Of the Rvo 3 Perovskitessupporting

confidence: 54%

“…Increasing angle ϑ causes a decrease of V-O-V bond angle along the c direction, being π − 2ϑ, and leads to an orthorhombic lattice distortion u = (b − a)/a, where a and b are the lattice parameters of the P bnm structure of RVO 3 . By the analysis of the structural data for the RVO 3 perovskites [103,104] one finds the following empirical relation between the ionic radius r R and the angle ϑ:…”

Section: Phase Diagram Of the Rvo 3 Perovskitesmentioning

confidence: 99%

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Charge and Orbital Order in Transition Metal Oxides

Oleś

2010

Acta Phys. Pol. A

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A short introduction to the complex phenomena encountered in transition metal oxides with either charge or orbital or joint charge-and-orbital order, usually accompanied by magnetic order, is presented. It is argued that all the types of above ordered phases in these oxides follow from strong Coulomb interactions as a result of certain compromise between competing instabilities towards various types of magnetic order and optimize the gain of kinetic energy in doped systems. This competition provides a natural explanation of the stripe order observed in doped cuprates, nickelates and manganites. In the undoped correlated insulators with orbital degrees of freedom the orbital order stabilizes particular types of anisotropic magnetic phases, and we contrast the case of decoupled (disentangled) spin and orbital degrees of freedom in the manganites with entangled spin-orbital states which decide about certain rather exotic phenomena observed in the perovskite vanadates at finite temperature. Examples of successful concepts in the theoretical approaches to these complex systems are given and some open problems of current interest are indicated. Degrees of freedom in transition metal oxidesThe physical properties of transition metal oxides are driven by strong electron interactions [1]. It is due to strong local Coulomb interactions that these systems exhibit very interesting and quite diverse instabilities towards ordered magnetic phases when doping x or temperature T is varied -is some cases also with orbital order. These instabilities are observed, inter alia, in rapid changes of the transport properties at the metalinsulator phase transitions, or in the onset of superconductivity.One of the outstanding problems in modern condensed matter theory is the description of strongly correlated electrons in various systems. When local Coulomb interactions are strong, the usual methods used for calculating the electronic structure fail and have to be extended by the terms following from local interactions, either in the framework of the local density approximation (LDA) with Coulomb U , the so-called LDA+U method [2], or by the self-energy within the dynamical mean-field theory (DMFT) [3], in the LDA + DMFT approach [4]. This latter approach makes use of the local self-energy which becomes exact in the limit of infinite spatial dimension d = ∞ [5]. However, even these methods cannot overcome certain shortcomings of the effective one-particle theory which justifies modelling of the transition metal * Dedicated to the memory of the late Professor Jan Stankowski. * * e-mail: a.m.oles@fkf.mpg.de oxides with Hamiltonians of the Hubbard type, and looking for solutions with methods of quantum many-body theory. The advantage of recent rapid progress in the electronic structure calculations is that such models can use realistic parameters nowadays, which follow from the electronic structure calculations for a given system. Although the field of strongly correlated electronic systems is very rich, we shall concentrate here on the phe...

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Section: Phase Diagram Of the Rvo 3 Perovskitessupporting

confidence: 54%

Section: Phase Diagram Of the Rvo 3 Perovskitesmentioning

confidence: 99%

Charge and Orbital Order in Transition Metal Oxides

Oleś

2010

Acta Phys. Pol. A

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“…The orbital interaction V c counteracts the orbital superexchange ∝ J (16), and has only rather weak dependence on ϑ , so it suffices to choose a constant V c = 0.26J to reproduce an almost simultaneous onset of spin and orbital order in LaVO 3 , with T OO ≃ T N1 , as observed [20]. One finds T exp N1 = 147 K taking J = 200 K in the present model (42), which reproduces well the experimental value T exp N1 = 143 K for LaVO 3 [20].…”

Section: Spin-orbital-lattice Couplingsupporting

confidence: 50%

“…It is clear that the nonmonotonic dependence of T OO on r R cannot be reproduced just by the superexchange, as a maximum in T OO requires two mechanisms which oppose each other. In fact, the decreasing V-O-V angle (Θ along the c axis) with decreasing ionic radius r R along the RVO 3 perovskites [40][41][42][43] reduces somewhat both the hopping t and superexchange J (6), but we shall ignore this effect here and concentrate ourselves on the leading dependence on orbital correlations which are controlled by lattice distortions.…”

Section: Spin-orbital-lattice Couplingmentioning

confidence: 99%

Orbital Fluctuations in the RVO3 Perovskites

Oleś¹,

Horsch²

2009

NATO Science for Peace and Security Series B: Physics and Biophysics

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The properties of Mott insulators with orbital degrees of freedom are described by spin-orbital superexchange models, which provide a theoretical framework for understanding their magnetic and optical properties. We introduce such a model derived for (xy) 1 (yz/zx) 1 configuration of V 3+ ions in the RVO 3 perovskites, R=Lu,Yb,· · ·,La, and demonstrate that {yz, zx} orbital fluctuations along the c axis are responsible for the huge magnetic and optical anisotropies observed in the almost perfectly cubic compound LaVO 3 . We argue that the GdFeO 3 distortion and the large difference in entropy of C-AF and G-AF phases is responsible for the second magnetic transition observed at T N2 in YVO 3 . Next we address the variation of orbital and magnetic transition temperature, T OO and T N1 , in the RVO 3 perovskites, after extending the spin-orbital model by the crystal-field and the orbital interactions which arise from the GdFeO 3 and Jahn-Teller distortions of the VO 6 octahedra. We further find that the orthorhombic distortion which increases from LaVO 3 to LuVO 3 plays a crucial role by controlling the orbital fluctuations, and via the modified orbital correlations influences the onset of both magnetic and orbital order.

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“…For [25], YbVO 3 [26] are not in conflict with this scenario. In addition, the inhomogeneity with RF model is different, but not inconsistent with, the coexistence, at low temperature, of a monoclinic and an orthorhombic phase found recently in a high resolution x-ray powder diffraction study of SmVO 3 [38]. To avoid complications arising due to the contribution from the rare-earth magnetism, we estimate the percentage of the RF spins only for the compounds with non magnetic rare-earths (i.e., LaVO 3 and YVO 3 ).…”

Section: Iv-discussionmentioning

confidence: 99%

Magnetization reversal in orthovanadateRVO3compounds (R=La, Nd, Sm, Gd, Er, and Y): Inhomogeneit

2007

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Abstract:We report on a study of various RVO 3 single-crystal samples (R = La, Nd, Sm, Gd, Er and Y) which show temperature-induced magnetization reversal. For compounds with lighter rare-earths (R = La, Nd and Sm), magnetization reversal can be observed for magnetic field applied in the ab plane and along the c axis, whereas for the heavy rare-earths (R = Gd, Er) magnetization reversal is only observed when the field is applied along the a axis. YVO 3 has a magnetization reversal along all the main crystallographic axes in a modest applied field. We have found that some compounds are very sensitive to small trapped fields present in the superconducting solenoid of the magnetometer during the cooling. Based on the observed results, we argue that inhomogeniety caused by defects in the orbital sector in the quasi onedimensional orbital systems could account for the unusual magnetization reversal.

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Evidence for Electronic Phase Separation between Orbital Orderings inSmVO3

Cited by 47 publications

References 20 publications

Charge and Orbital Order in Transition Metal Oxides

Charge and Orbital Order in Transition Metal Oxides

Orbital Fluctuations in the RVO3 Perovskites

Magnetization reversal in orthovanadateRVO3compounds (R=La, Nd, Sm, Gd, Er, and Y): Inhomogeneit

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