We study numerically the one-dimensional ferromagnetic Kondo lattice model, which is widely used ... more We study numerically the one-dimensional ferromagnetic Kondo lattice model, which is widely used to describe nickel and manganese perovskites. We find broad regions near the commensurate dopings where the formation of magnetic polarons induces a charge-ordered state. This ordering arises from the competition between double and super-exchange, and is present even in the absence of any inter-site Coulomb repulsion. An
We study numerically the one-dimensional ferromagnetic Kondo lattice model, which is widely used ... more We study numerically the one-dimensional ferromagnetic Kondo lattice model, which is widely used to describe nickel and manganese perovskites. We find broad regions near the commensurate dopings where the formation of magnetic polarons induces a charge-ordered state. This ordering arises from the competition between double and super-exchange, and is present even in the absence of any inter-site Coulomb repulsion. An
A new numerical method for the solution of the Dynamical Mean Field Theory's self-consistent equa... more A new numerical method for the solution of the Dynamical Mean Field Theory's self-consistent equations is introduced. The method uses the Density Matrix Renormalization Group technique to solve the associated impurity problem. The new algorithm makes no a priori approximations and is only limited by the number of sites that can be considered. We obtain accurate estimates of the critical values of the metal-insulator transitions and provide evidence of substructure in the Hubbard bands of the correlated metal. With this algorithm, more complex models having a larger number of degrees of freedom can be considered and finite-size effects can be minimized. PACS numbers: 71.10.Fd, 71.27.+a, 71.30.+h Great theoretical progress in our understanding of the physics of strongly correlated electron systems has been possible since the introduction of the Dynamical Mean Field Theory (DMFT) just over ten years now . This approach is based on the natural extension of the familiar classical mean-field theory of statistical mechanics to the treatment of models of strongly interacting electrons on a lattice. The DMFT solution of the model is exact in the limit of large lattice dimensionality or large connectivity [2, 3]. Since its introduction, DMFT has been widely adopted and was used for the investigation of a large variety of model Hamiltonians relevant for problems as diverse as colossal magneto-resistance, heavy fermions, metal-insulator transitions, etc. . A great deal of interest is currently centered around the ongoing efforts to incorporate DMFT as the local correlation physics "engine" for first-principle calculations of realistic compounds . At the heart of the DMFT method is the solution of an associated quantum impurity model where the environment of the impurity has to be determined self-consistently. Therefore the ability to obtain reliable DMFT solutions of lattice model Hamiltonians relies directly on the ability to solve quantum impurity models. Since solutions of general impurity models are usually not analytically tractable, one has to resort to numerical algorithms or approximate methods. Among the a priori exact numerical algorithms available we count the Hirsch-Fye Quantum Monte Carlo [6] method and Wilson's Numerical Renormalization Group (NRG) . The former is a finite-temperature method that is formulated in imaginary time and has been applied to a large variety of impurity models including the multi-orbital case that corresponds to correlated multi-band lattice Hamiltoni- * Present address: DFMC, Unicamp, Campinas, São Paulo, Brasil.
We study numerically the one-dimensional ferromagnetic Kondo lattice model, which is widely used ... more We study numerically the one-dimensional ferromagnetic Kondo lattice model, which is widely used to describe nickel and manganese perovskites. We find broad regions near the commensurate dopings where the formation of magnetic polarons induces a charge-ordered state. This ordering arises from the competition between double and super-exchange, and is present even in the absence of any inter-site Coulomb repulsion. An
We study numerically the one-dimensional ferromagnetic Kondo lattice model, which is widely used ... more We study numerically the one-dimensional ferromagnetic Kondo lattice model, which is widely used to describe nickel and manganese perovskites. We find broad regions near the commensurate dopings where the formation of magnetic polarons induces a charge-ordered state. This ordering arises from the competition between double and super-exchange, and is present even in the absence of any inter-site Coulomb repulsion. An
A new numerical method for the solution of the Dynamical Mean Field Theory's self-consistent equa... more A new numerical method for the solution of the Dynamical Mean Field Theory's self-consistent equations is introduced. The method uses the Density Matrix Renormalization Group technique to solve the associated impurity problem. The new algorithm makes no a priori approximations and is only limited by the number of sites that can be considered. We obtain accurate estimates of the critical values of the metal-insulator transitions and provide evidence of substructure in the Hubbard bands of the correlated metal. With this algorithm, more complex models having a larger number of degrees of freedom can be considered and finite-size effects can be minimized. PACS numbers: 71.10.Fd, 71.27.+a, 71.30.+h Great theoretical progress in our understanding of the physics of strongly correlated electron systems has been possible since the introduction of the Dynamical Mean Field Theory (DMFT) just over ten years now . This approach is based on the natural extension of the familiar classical mean-field theory of statistical mechanics to the treatment of models of strongly interacting electrons on a lattice. The DMFT solution of the model is exact in the limit of large lattice dimensionality or large connectivity [2, 3]. Since its introduction, DMFT has been widely adopted and was used for the investigation of a large variety of model Hamiltonians relevant for problems as diverse as colossal magneto-resistance, heavy fermions, metal-insulator transitions, etc. . A great deal of interest is currently centered around the ongoing efforts to incorporate DMFT as the local correlation physics "engine" for first-principle calculations of realistic compounds . At the heart of the DMFT method is the solution of an associated quantum impurity model where the environment of the impurity has to be determined self-consistently. Therefore the ability to obtain reliable DMFT solutions of lattice model Hamiltonians relies directly on the ability to solve quantum impurity models. Since solutions of general impurity models are usually not analytically tractable, one has to resort to numerical algorithms or approximate methods. Among the a priori exact numerical algorithms available we count the Hirsch-Fye Quantum Monte Carlo [6] method and Wilson's Numerical Renormalization Group (NRG) . The former is a finite-temperature method that is formulated in imaginary time and has been applied to a large variety of impurity models including the multi-orbital case that corresponds to correlated multi-band lattice Hamiltoni- * Present address: DFMC, Unicamp, Campinas, São Paulo, Brasil.
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Papers by Daniel Garcia