Related papers: Doping change and distortion effect on double-exch…
The superconducting properties of a recently proposed phenomenological model for a weakly doped antiferromagnet are analyzed, taking into account fluctuations of the phase of the order parameter. In this model, we assume that the doped…
Recent experiments on the amorphous magnetic semiconductor Gd_x Si_{1-x}, Phys. Rev. Lett. 77, 4652 (1996), ibid 83, 2266 (1999), ibid 84, 5411 (2000), ibid 85, 848 (2000), have revealed an insulator-metal transition (i-m-t), as a function…
A Falicov-Kimball model which thermodynamically reduces the local Coulomb interaction of particles to attraction or repulsion is studied within the dynamical mean-field theory. In the strong interaction regime a fractionalization of…
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…
We use resonant elastic and inelastic X-ray scattering at the Ir-$L_3$ edge to study the doping-dependent magnetic order, magnetic excitations and spin-orbit excitons in the electron-doped bilayer iridate (Sr$_{1-x}$La$_{x}$)$_3$Ir$_2$O$_7$…
Dilute magnetic semiconductors (DMS) are nonmagnetic semiconductors doped with magnetic transition metals. The recently discovered DMS material (Ba$_{1-x}$K$_{x}$)(Zn$_{1-y}$Mn$_{y}$)$_{2}$As$_{2}$ offers a unique and versatile control of…
We use first-principles density functional theory to investigate how the polar distortion is affected by doping in multiferroic hexagonal yttrium manganite, h-YMnO$_3$. While the introduction of charge carriers tends to suppress the polar…
We study the doping evolution of spin excitations in a 1D Hubbard model and its downfolded spin Hamiltonians, by using exact diagonalization combined with cluster perturbation theory. In all models, we observe hardening (softening) of spin…
Using a recently proposed Ginzburg-Landau-like lattice free energy functional due to Banerjee et al. Phys. Rev. B 83, 024510 (2011) we calculate the fluctuation diamagnetism of high-Tc superconductors as a function of doping, magnetic field…
To shed light on how electronic correlations vary across the phase diagram of the cuprate superconductors, we examine the doping evolution of spin and charge excitations in the single-band Hubbard model using determinant quantum Monte Carlo…
In the CMR materials, ferromagnetic double exchange (DE) presumably coexists with a direct nearest-neighbour antiferromagnetic interaction. We construct a single-site mean field theory that explicitly takes into account the different nature…
A coupled spin-electron chain composed of localized Ising spins and mobile electrons is exactly solved in an external magnetic field within the transfer-matrix method. The ground-state phase diagram involves in total seven different ground…
The magnon energy and amplitude renormalization due to intraband particle-hole excitations are studied in a metallic antiferromagnet. The change in sign of the intraband contribution with $\omega$ results in significant differences between…
We calculate the temperature of a ferromagnetic transition in a double-exchange model with classical core spins for arbitrary relation between Hund exchange coupling and electron band width by solving the Dynamical Mean Field Approximation…
We use combine high resolution neutron diffraction (HRPD) with density functional theory (DFT) to investigate the exchange striction at the Curie temperature (TC) of Fe2P and to examine the effect of boron and carbon doping on the P site.…
A two-site double exchange model with a single polaron is studied using a perturbation expansion based on the modified Lang-Firsov transformation. The antiferromagnetic to ferromagnetic transition and the crossover from small to large…
In this manuscript, recent theoretical investigations by the authors in the area of oxide multilayers are briefly reviewed. The calculations were carried out using model Hamiltonians and a variety of non-perturbative techniques. Moreover,…
Magnetic properties of the two-dimensional spin-polarized Fermi gas with dipole-dipole interaction are studied in the presence of external magnetic field at zero temperature. Within perturbation theory and the second quantization formalism,…
Nesting in a semimetal can lead to an excitonic insulator state with spontaneous coherence between conduction and valence bands and a gap for charged excitations. In this paper we present a theory of the ferromagnetic state that occurs when…
This work analyzes the behavior of the interface between a ferromagnetic material and an alter-magnet. We use a well-established line of arguments based on electronic mean-field calculations to show that new surface phenomena that lead to…