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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 12 of 12 for “"Orbital ordering"”.
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X-Ray Scattering Studies of Charge and Orbital Ordering in Transition Metal Oxides
This thesis focusses on the phenomena of charge ordering and orbital ordering in transition metal oxides, using the technique of resonant x-ray diffraction (RXD). The technique is suited to such studies, as it provides an elemental and band specific probe of long range electronic correlations. …
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X-ray scattering studies of strongly correlated materials: orbital ordering in KCuF3 and stripe-like domain structures in BiFeO3 epitaxial thin films
The results of x-ray scattering experiments on orbitally ordered KCuF3 and periodic arrays of stripe-like ferroelectric domains in epitaxial thin films of multiferroic BiFeO3 are presented in this dissertation. Both resonant soft x-ray elastic scattering and non-resonant hard x-ray elastic …
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Exploring the pressure- and magnetic-field-induced phases of orbital-ordering KCuF3 and single molecule magnet Mn12-acetate: Crystal growth and Raman scattering studies
… to probe the novel phases and properties of the orbital ordering material KCuF3 and the single molecule magnet Mn12-acetate as functions of temperature, applied pressure, and applied magnetic field. Single crystal samples of KCuF3, Mn12-acetate, 1T-TiSe2, and Bi2Se3 are also grown as part of this …
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Raman Scattering Studies of the Orbital, Magnetic, and Conducting Phases in Double Layer Ruthenates
… This addition of La also lowers the orbital ordering temperature to T ∼ 43 K, and provides a greater sensitivity of the orbital phases to applied magnetic fields, as evidenced by changes in the phases occurring at lower fields and over a greater field range than seen in the …
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Raman spectroscopy: from ferroelastic domain identification to strain tuning
… temperature induced phase transitions or orbital ordering, which are intimately related to specific phonon modes, as in the case of BiCrO3 or LaVO3, respectively. A method based on the Raman tensor formalism, which allows an assignment of the BiFeO3 Raman modes of pure as well as mixed …
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Frustrated Magnetism in Strongly Correlated Electron Systems
… correlated electron systems, where exotic orderings can be induced as a result of magnetic frustration and quantum fluctuations. We show that emergent spin textures can arise close to a magnetic field-induced quantum critical point, when the single magnon excitations have several degenerate …
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Complex phase behavior of exotic oxides: optical spectroscopy studies
… correlations among charge, lattice, spin, and/or orbital degrees of freedom. In the low doping regime of R1_xDxMn03 (0.2 :::; x :::; 0.5), where a paramagnetic insulator to ferromagnetic metal transition takes place with a large value of magnetoresistance at the transition, we observed that …
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Raman scattering studies of spinels CoV2O4 and MnV2O4
… The absence of a structural distortion in orbitally degenerate CoV2O4 supports the previous speculation that the t2g valence electrons in CoV2O4 are not localized. In our pressure-dependent studies, we discover a pressure-induced symmetry-lowering structural transition for P ~ 40 kbar and …
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Inelastic light scattering studies of quantum phase transitions in CuxTiSe2 and multiferroic TbMnO3
… coupling between charge, spin, lattice and orbital degrees of freedom. Because of the inter- play between various competing orders, these systems have highly complex phase diagrams and exhibit interesting phenomena such as colossal magnetoresistance (CMR), high temperature superconductivity …
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Ladungs- und Orbitalordnungsphänomene in Übergangsmetalloxidverbindungen unter hydrostatischem Druck
… is dealing with the investigation of charge and orbital order and their behaviour under external pressure. Therefore, a new pressure cell has been developed which allows the observation of superlattice reflections corresponding to the order phenomena under pressure using scattering of high-energy …
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Non-perturbative approaches to strongly correlated electron systems
… will then be reviewed. In chapter 2, the two-orbital Hubbard model with degenerate d{xz} and d{yz} orbitals are investigated. We apply multidimensional bosonization to solve this problem exactly and discover a z=3 overdamped collective modes that emerges at the orbital-ordering quantum …
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Geometric frustration in high spin orbit coupling magnetic materials
… both as a frustrated insulator with unquenched orbital degeneracy and as a near-itinerant magnet which can be driven metallic with moderate applied pressure. Here, we report on our recent neutron diffraction and inelastic scattering measurements on powders and epitaxial thin films. In both …