270 research outputs found

    Spatial inhomogeneity and strong correlation physics: a dynamical mean field study of a model Mott-insulator/band-insulator heterostructure

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    We use the dynamical mean field method to investigate electronic properties of heterostructures in which finite number of Mott-insulator layers are embedded in a spatially infinite band-insulator. The evolution of the correlation effects with the number of Mott insulating layers and with position in the heterostructure is determined, and the optical conductivity is computed. It is shown that the heterostructures are generally metallic, with moderately renormalized bands of quasiparticles appearing at the interface between the correlated and uncorrelated regions.Comment: 4 pages, 4 figure

    Role of oxygen-oxygen hopping in the three-band copper-oxide model: quasiparticle weight, metal insulator and magnetic phase boundaries, gap values and optical conductivity

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    We investigate the effect of oxygen-oxygen hopping on the three-band copper-oxide model relevant to high-TcT_c cuprates, finding that the physics is changed only slightly as the oxygen-oxygen hopping is varied. The location of the metal-insulator phase boundary in the plane of interaction strength and charge transfer energy shifts by 0.5\sim 0.5eV or less along the charge transfer axis, the quasiparticle weight has approximately the same magnitude and doping dependence and the qualitative characteristics of the electron-doped and hole-doped sides of the phase diagram do not change. The results confirm the identification of La2_2CuO4_4 as a material with intermediate correlation strength. However, the magnetic phase boundary as well as higher-energy features of the optical spectrum are found to depend on the magnitude of the oxygen-oxygen hopping. We compare our results to previously published one-band and three-band model calculations.Comment: 13.5 pages, 16 figure

    Adaptively truncated Hilbert space based impurity solver for dynamical mean-field theory

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    We present an impurity solver based on adaptively truncated Hilbert spaces. The solver is particularly suitable for dynamical mean-field theory in circumstances where quantum Monte Carlo approaches are ineffective. It exploits the sparsity structure of quantum impurity models, in which the interactions couple only a small subset of the degrees of freedom. We further introduce an adaptive truncation of the particle or hole excited spaces, which enables computations of Green functions with an accuracy needed to avoid unphysical (sign change of imaginary part) self-energies. The method is benchmarked on the one-dimensional Hubbard model.Comment: 10 pages, 7 figure

    Transient trapping into metastable states in systems with competing orders

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    The quench dynamics of a system involving two competing orders is investigated using a Ginzburg-Landau theory with relaxational dynamics. We consider the scenario where a pump rapidly heats the system to a high temperature, after which the system cools down to its equilibrium temperature. We study the evolution of the order parameter amplitude and fluctuations in the resulting time dependent free energy landscape. Exponentially growing thermal fluctuations dominate the dynamics. The system typically evolves into the phase associated with the faster-relaxing order parameter, even if it is not the global free energy minimum. This theory offers a natural explanation for the widespread experimental observation that metastable states may be induced by laser induced collapse of a dominant equilibrium order parameter.Comment: 12 pages, 7 figure
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