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Fujioka, Jun; Miyasaka, S.; Tokura, Y.

doi:10.1103/physrevb.77.144402

Cited by 41 publications

(48 citation statements)

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“…The subsistence of the two-magnon band is also seen in the hole doping induced C-type spin/G-type orbital ordered phase for Y 1−x Ca x VO 3 , and is interpreted in terms of the spin/orbital dynamical fluctuation. 18 As previously mentioned, the phase transition between the G-type spin/C-type orbital ordered state and the C-type spin /G-type orbital ordered one is, however, of first order. Thus, the dynamical fluctuation of the G-type SO/C-type OO in the nominally C-type spin/G-type orbital ordered phase at temperatures as low as 4.3 K would be unlikely.…”

Section: A Two-phase Competition In Y 1−x Eu X Vomentioning

confidence: 84%

Critical competition between two distinct orbital-spin ordered states in perovskite vanadates

et al. 2010

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We have investigated the spin/orbital phase diagram in the perovskite orthovanadate RVO 3 ͑R = Eu, Y, Dy, and Ho͒ by measurements of magnetization, dielectric constant, specific heat, Raman scattering spectra, and x-ray diffraction, focusing on the interplay between the V 3d spin and the 4f moment of the R ion. The thermally induced phase transition between the C-type spin/G-type orbital ordered state and the G-type spin/ C-type orbital ordered state is observed for Eu 1−x Y x VO 3 ͑x = 0 -0.52͒ without 4f moment. By comparing this phase diagram with the spin/orbital ordering in TbVO 3 , it is evident that the critical competition between the C-type spin/G-type orbital ordered phase and the G-type spin/C-type orbital ordered one depends not only on the GdFeO 3 -type lattice distortion but also on the presence of the 4f moment of the R ion. The magnetic field induced phase transition of the spin/orbital ordering is achieved concomitantly with polarizing R 4f moments for DyVO 3 and HoVO 3 . For DyVO 3 , the G-type spin/C-type orbital ordered phase is switched to the C-type spin/G-type orbital ordered one by applying a moderate magnetic field around 3 T. By contrast, the G-type spin/C-type orbital ordering is rather favored under the magnetic field in HoVO 3 . The results cannot be uniquely explained in terms of the exchange interaction between the V 3d spin and the R-ion 4f moment. The coupling of the R 4f moment polarization with the lattice distortion tied with the orbital ordering of the V 3d sublattice may also be relevant to this field induced phase transition.

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Section: A Two-phase Competition In Y 1−x Eu X Vomentioning

confidence: 84%

Critical competition between two distinct orbital-spin ordered states in perovskite vanadates

et al. 2010

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“…The gradual changes of the optical conductivity under increasing doping demonstrate that the anisotropy between the ab and c direction decreases, but surprisingly is not completely lost even in the metallic regime. The differences observed in the optical conductivity and Raman scattering spectra between La 1−x Sr x VO 3 and Y 1−x Sr x VO 3 suggest that the orthorhombic lattice distortion plays also here a very important role and influences the hole dynamics [126]. It has been argued that the C-AF phase is more robust under hole doping [127] and survives in a broad doping range [128], but a complete understanding of doped vanadate perovskites awaits a more careful theoretical study.…”

Section: Coexisting Charge and Orbital Ordermentioning

confidence: 99%

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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“…The influence of the orbital degrees of freedom of the d electrons on the magnetic and transport properties of metal-oxide compounds has attracted much attention in recent years [1]. Mott-insulating orthovanadates of chemical composition RVO 3 (R = Y or a trivalent rare-earth metal) have been widely studied as a model system of the coupling between the spin and orbital degrees of freedom [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. The valence electrons on the V 3+ ions (electron configuration 3d…”

Section: Introductionmentioning

confidence: 99%

“…The evolution of spin-orbital-lattice coupling in RVO 3 perovskites was described in a microscopic spin-orbital model, where the ionic radius r(R 3+ ) affects the V-O-V bonds and hence the orbital-dependent superexchange interactions between the vanadium spins [25]. In this paper, we focus on the influence of hole doping on the microscopic spin and orbital correlations in Pr 1−x Ca x VO 3 , following up on prior work on the doping dependence of the macroscopic magnetic, optical, and transport properties of Pr 1−x Ca x VO 3 , as well as other hole-doped vanadates, including La 1−x Sr x VO 3 , Nd 1−x Sr x VO 3 , and Y 1−x Ca x VO 3 [8][9][10][11][12][13]. In general, the partial replacement of the R 3+ ions by divalent alkaline-earth ions A 2+ = Ca 2+ or Sr 2+ induces holes in the t 2g electronic level of the V 3+ ions.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, modifications of the one-electron bandwidth through changes in the crystal structure induced by chemical substitution are also expected (Refs. [8][9][10][11][12][13] and [26]), and the substitutional disorder can strongly affect the transport and optical properties [27][28][29][30]. Calcium doped PrVO 3 can be considered as a special case because the ionic radii of Pr 3+ (1.126Å) and Ca 2+ (1.120Å) are almost identical (see Ref.…”

Section: Introductionmentioning

confidence: 99%

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Spin and orbital disordering by hole doping inPr1−xCaxVO3<

et al. 2016

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High-resolution powder x-ray diffraction and single-crystal neutron diffraction were used to investigate the crystal structure and magnetic ordering of the compound Pr 1−x Ca x VO 3 (0 x 0.3), which undergoes an insulator-to-metal transition for x ∼ 0.23. Since the ionic radii of Pr 3+ and Ca 2+ are almost identical and structural disorder is minimal, Pr 1−x Ca x VO 3 is a good model system for the influence of hole doping on the spin and orbital correlations in transition metal oxides. The end member PrVO 3 is a Mott-Hubbard insulator, which exhibits a structural phase transition at T S = 180 K from an orthorhombic to a monoclinic structure with space groups Pbnm and P 2 1 /b, respectively. This transition is associated with the onset of orbital ordering and strong Jahn-Teller distortions of the VO 6 octahedra. Antiferromagnetic C-type order with vanadium moments oriented in the ab plane is observed below T N = 140 K. Upon cooling, the vanadium moments induce a progressive magnetic polarization of the praseodymium sublattice, resulting in a ferrimagnetic structure with coexisting modes (C x , F y ) and (F x , C y ). In the insulating range of the Pr 1−x Ca x VO 3 phase diagram, Ca doping reduces both the orbital and magnetic transition temperatures so that T S = 108 K and T N = 95 K for x = 0.20. The Jahn-Teller distortions and ordered vanadium moments also decrease upon doping. In a metallic sample with x = 0.30, Jahn-Teller distortions and long-range orbital ordering are no longer observable, and the average crystal structure remains orthorhombic down to low temperature. However, broadening of some lattice Bragg reflections indicate a significant increase in lattice strain. Antiferromagnetic short-range order with a weak ordered moment of 0.14(3) μ B per vanadium atom could still be observed on the vanadium site below T ∼ 60 K. We discuss these observations in terms of doping-induced spin-orbital polaron formation.

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Doping variation of anisotropic charge and orbital dynamics inY1−xCaxVO3: Comparison with
Jun Fujioka
¹
,
S. Miyasaka²,
Y. Tokura
³

Cited by 41 publications

References 35 publications

Critical competition between two distinct orbital-spin ordered states in perovskite vanadates

Critical competition between two distinct orbital-spin ordered states in perovskite vanadates

Charge and Orbital Order in Transition Metal Oxides

Spin and orbital disordering by hole doping inPr1−xCaxVO3<

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Doping variation of anisotropic charge and orbital dynamics inY1−xCaxVO3: Comparison withJun Fujioka1, S. Miyasaka2, Y. Tokura3

Cited by 41 publications

References 35 publications

Critical competition between two distinct orbital-spin ordered states in perovskite vanadates

Critical competition between two distinct orbital-spin ordered states in perovskite vanadates

Charge and Orbital Order in Transition Metal Oxides

Spin and orbital disordering by hole doping inPr1−xCaxVO3<

Contact Info

Product

Resources

About

Doping variation of anisotropic charge and orbital dynamics inY1−xCaxVO3: Comparison with
Jun Fujioka
¹
,
S. Miyasaka²,
Y. Tokura
³