Related papers: Ground State of the Double Exchange Model
We study the low energy properties of the one-orbital quantum double-exchange model by using the slave fermion formulation. We construct a mean-field theory which gives a simple explanation for the magnetic and thermodynamic properties of…
We investigate the phase diagram of an extended Kondo lattice model for doped manganese oxides in the presence of strong but finite Hund's coupling and on-site Coulomb interaction. By means of the Schwinger-boson mean-field approach, it is…
The influence of local electronic correlations on the properties of colossal magnetoresistance manganites is investigated. To this end, a ferromagnetic two-band Kondo lattice model is supplemented with the local Coulomb repulsion missing in…
Phase diagram and critical properties are studied for three-dimensional double exchange model with and without quenched disorder. Employing the Monte Carlo method and the systematic analysis on the finite-size effect, we estimate the Curie…
The double exchange (DE) model is systematically applied for studying the coupling between ferroelectric (FE) and magnetic orders in several prototypical types of multiferroic manganites. The model was constructed for the magnetically…
We present extensive large-scale dynamical simulations of phase-separated states in the double exchange model. These inhomogeneous electronic states that play a crucial role in the colossal magnetoresistance phenomenon are composed of…
We have studied structural, magnetic and transport properties as a function of temperature and magnetic field in the electron doped manganite YxCa1-xMnO3, for 0<x<0.25. We found that in the paramagnetic regime, the magnetic susceptibility,…
The physics of ferromagnetic doped manganites, such as \chem{La_{1-x}Ca_xMnO_3} with $x\approx0.2$--0.4, is reviewed. The concept of double exchange is discussed within the general framework of itinerant electron magnetism. The new feature…
We study the competition between different possible ground states of the double-exchange model with strong ferromagnetic exchange interaction between itinerant electrons and local spins. Both for classical and quantum treatment of the local…
The coexistence of ferromagnetism and metallic conduction in doped manganites has long been explained by a double-exchange model in which the ferromagnetic exchange arises from the carrier hopping. We evaluate the zero-temperature spin…
The Monte Carlo Ferromagnetic Ising model was used to study the electrical properties of manganese oxides due to the charge ordering phase occurring at doping, x = 0.5. The half-doped manganites have an insulator antiferromagnetic ground…
We introduce a microscopic model for electron doped manganites that explains the mechanism of the observed transition from $G$-type antiferromagnetic ($G$-AF) to $C$-type antiferromagnetic ($C$-AF) order under increasing doping by double…
The surface magnetic phase transition of a double-exchange model for metallic manganites is studied using a Schwinger-boson mean-field method. About three unit-cells wide surface layers are identified. The magnetic moment in these layers…
Spin-state transitions, observed in many transition metal compounds containing Co$^{3+}$ and Fe$^{2+}$, may occur with the change of temperature, pressure, but also with doping, in which case the competition of single-site effects and…
This paper is a brief review of our recent studies concerning on magnetism and electronic states of lattice systems with Hund coupling. First we examined the effectiveness of the Hund coupling in realizing ferromagnetism in the doubly…
A comprehensive analysis of half-doped manganites is presented using Monte Carlo simulations applied to the double-exchange model with cooperative Jahn-Teller lattice distortions in two dimensions. A variety of novel results are reported:…
In response to the experimental discovery of double perovskite Ru- base material, The magnetic and electronic properties of the double exchange mechanism are studied theoretically. The electron band structure and the spin wave spectrum…
We present a simplified model for the colossal magnetoresistance in doped manganites by exactly solving a double-exchange model (with Ising-like local spins) and quenched binary disorder within dynamical mean field theory. We examine the…
A double exchange model for degenerate $e_g$ orbitals with intra- and inter-orbital interactions has been studied for the electron doped manganites A$_{1-x}$B$_{x}$MnO$_3$ ($x > 0.5$). We show that such a model reproduces the observed phase…
The (001) surface of La_{1-x}Ca_xMnO_3 system in various magnetic orderings is studied by first principle calculations. A general occurrence is that z^2 dangling bond charge -- which is ``invisible'' in the formal valence picture -- is…