Related papers: Orbital ordering and magnetic structures in $\LMFO…
We consider magnetic ordering in materials with negative charge transfer energy, such as iron perovskite oxides. We show that for a large weight of oxygen holes in conduction bands, the double exchange mechanism favors a helicoidal rather…
In addition to the well known ferromagnetism, double perovskites are also expected to exhibit antiferromagnetic (AF) order driven by electron delocalisation. This has been seen in model Hamiltonian studies and confirmed via ab initio…
Double perovskites of the form A_2BB'O_6 usually involve a transition metal ion, B, with a large magnetic moment, and a non magnetic ion B'. While many double perovskites are ferromagnetic, studies on the underlying model reveal the…
We formulate a superexchange theory of insulating double-perovskite compounds such as Sr$_2$FeWO$_6$. An effective spin-orbital Hamiltonian is derived in the strong coupling limit of Hubbard model for d-electrons on Fe and W ions. The…
Magnetic double perovskite compounds provide a fertile playground to explore interesting electronic and magnetic properties. By complementary macroscopic characterizations, neutron powder diffraction measurements and first-principles…
Magnetic structures and the relationship between spin and charge-orbital orderings of an A-site ordered double-perovskite manganite SmBaMn2O6, an anticipated multiferroic material, were investigated by means of neutron diffraction. The spin…
Motivated by recent experimental progress in transition metal oxides with the K$_2$NiF$_4$ structure, we investigate the magnetic and orbital ordering in $\alpha$-Sr$_2$CrO$_4$. Using first principles calculations, first we derive a…
Phase diagram of half-doped perovskite manganites is studied within the extended double-exchange model. To demonstrate the role of orbital degrees of freedom both one- and two-orbital models are examined. A rich phase diagram is obtained in…
We report on atomic ordering of B-site transition-metals and magnetic properties of epitaxial La2CrFeO6 double-perovskite films grown by pulsed-laser deposition under various conditions. The highest ordered sample exhibited a fraction of…
We apply a Hartree-Fock approximation to a two-orbital model proposed for Fe pnictide superconductors. It is found that the antiferromagnetic (AFM) order with the ordering vector Q=(pi,0) is realized. The AFM order appears simultaneously…
We attribute the structural phase transition (SPT) in the parent compounds of the iron pnictides to orbital ordering. Due to the anisotropy of the $d_{xz}$ and $d_{yz}$ orbitals in the $xy$ plane, a ferro-orbital ordering makes the…
Motivated by the time-reversal symmetry breaking signal in muon spin relaxation below a transition temperature without accompanying noticeable magnetic Bragg peaks in $5d^2$ Os double perovskites, a rare ferro-octupolar order was proposed…
{\it Ab-initio} studies of the stability of orbital ordering, its coupling to magnetic structure and its possible origins (electron-phonon and/or electron-electron interactions) are reported for two perovskite systems, LaMnO$_3$ and…
Metals with large positive magnetoresistance are rare. We demonstrate that antiferromagnetic metallic states, as have been predicted for the double perovskites, are excellent candidates for huge positive magnetoresistance. An applied field…
We report the comprehensive experimental results identifying the magnetic spin ordering and the magnetization dynamics of a double perovskite Pr2CoFeO6 by employing the (dc and ac) magnetization, powder neutron diffraction (NPD) and X-ray…
The two-orbital double-exchange model is employed for the study of the magnetic and orbital orders in ($R$MnO$_3$)$_n$/($A$MnO$_3$)$_{2n}$ ($R$: rare earths; $A$: alkaline earths) superlattices. The A-type antiferromagnetic order is…
We analyze the metallic (pi,0) antiferromagnetic state of a five-orbital model for iron superconductors. We find that with increasing interactions the system does not evolve trivially from the pure itinerant to the pure localized regime.…
The spin and orbital phase diagram for perovskite manganites are investigated as a function of temperature and hole concentration. The superexchange and double exchange interactions dominate the ferromagnetic phases in the low and high…
We consider strongly spin-orbit coupled double perovskites A$_2$BB'O$_6$ with B' magnetic ions in either $d^1$ or $d^2$ electronic configuration and non-magnetic B ions. We provide insights into several experimental puzzles, such as the…
We study the effects of temperature and magnetic field on a two-orbital Hubbard model within dynamical mean field theory. We focus on the quarter filled system, which is a special point in the phase diagram due to orbital degeneracy. At…