Related papers: Ferromagnetic Polarons in Manganites
Most previous investigations have shown that the surface of a ferromagnetic material may have antiferromagnetic tendencies. However, experimentally the opposite effect has been recently observed: ferromagnetism appears in some nano-sized…
We report on the influence of the lattice degrees of freedom on charge, orbital and spin correlations in colossal magnetoresistance (CMR) manganites. For the weakly doped compounds we demonstrate that the electron-phonon coupling promotes…
It is shown that the double exchange Hamiltonian, with weak antiferromagnetic interactions, has a rich variety of first order transitions between phases with different electronic densities and/or magnetizations. For band fillings in the…
We present a simpler derivation of the exact solution of a spin-polaron in a ferromagnet and generalize it to complex lattices and/or longer range exchange interactions. As a specific example, we analyze a two-dimensional MnO$_2$-like…
The Hubbard-Holstein model is studied including double-exchange interaction and superexchange interaction using a variational phonon basis obtained through the modified Lang-Firsov (MLF) transformation followed by the squeezing…
The growth of charge ordering phenomenon in calcium doped lanthanum manganites La1-xCaxMnO3, x 0.62, 0.67 has been studied using transmission electron microscopy TEM. The diffuse intensity characteristic of short range charge ordering is…
Oxygen-isotope effects on the intrinsic resistivity have been studied in high-quality epitaxial thin films of La_{0.75}Ca_{0.25}MnO_{3} and Nd_{0.7}Sr_{0.3}MnO_{3}. We found that the residual resistivity \rho_{o} increases by about 15(3)%…
In this work, we study the magnetization dynamics in a ferromagnet/insulator/ferromagnet trilayer sandwiched between two superconductors (S/F/I/F/S heterostructure). It is well-known that a conceptually similar S/F/S system is a platform…
Obtaining strong magnetoelectric couplings in bulk materials and heterostructures is an ongoing challenge. We demonstrate that manganite heterostructures of the form ${\rm (Insulator)/(LaMnO_3)_n/(CaMnO_3)_n/(Insulator)}$ show strong…
Obtaining strong magnetoelectric couplings in bulk materials and heterostructures is an ongoing challenge. We demonstrate that manganite heterostructures of the form ${\rm (Insulator)/(LaMnO_3)_n/(CaMnO_3)_n/(Insulator)}$ show strong…
The low temperature behavior of Pr$_{1-x}$Ca$_{x}$MnO$_{3}$ manganites are known to undergo a transition at $x\sim$0.3, from an insulating ferromagnetic state, at low Ca concentration, to an insulating antiferromagnetic state. Above the…
Collinear antiferromagnets (AFs) support two degenerate magnon excitations carrying opposite spin polarizations, by which magnons can function as electrons in various spin-related phenomena. In an insulating ferromagnet(F)/AF/F trilayer, we…
The optical conductivity of the undoped PrMnO$_3$ manganite has been investigated in details at various temperatures between 300 and 4 K. Its low energy spectrum exhibits an optical gap, and is characterized by a single broad peak centered…
We consider a model with competing double-exchange (ferromagnetic) and super-exchange (anti-ferromagnetic) interactions in the regime where phase separation takes place. The presence of a long range Coulomb interaction frustrates a…
Using the degenerate double exchange Hamiltonian with on-site Coulomb interactions we show that there is an instability towards the displacement of the manganese ion in La_{1-x}Ca_{x}MnO_{3}. The result is a dipole moment due to the charge…
Based on the Holstein double-exchange model and a highly efficient single cluster Monte Carlo approach we study the interplay of double-exchange and polaron effects in doped colossal magneto-resistance (CMR) manganites. The CMR transition…
The structure of bound magnetic polarons in an antiferromagnetic matrix is studied in the framework of two-dimensional (2D) and three-dimensional (3D) Kondo-lattice models in the double exchange limit (J_H >> t). The conduction electron is…
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…
Inspired by the strong experimental evidence for the coexistence of localized and itinerant charge carriers close to the metal-insulator transition in the ferromagnetic phase of colossal magnetoresistive manganese perovskites, for a…
Unrestricted Hartree-Fock calculations on La0.5Ca0.5MnO3 and La0.33Ca0.67MnO3 in the full magnetic unit cell show that the magnetic ground states of these compounds consist of 'ferromagnetic molecules' or polarons ordered in herring-bone…