Related papers: Doping Induced Spin State Transition in LaCoO3: Dy…
Doping change and distortion effect on the double-exchange ferromagnetism are studied within a simplified double-exchange model. The presence of distortion is modelled by introducing the Falicov-Kimball interaction between itinerant…
Low energy spin fluctuations are studied for the electron-doped Fe-based superconductor LaFeAsO(1-x)F(x) by inelastic neutron scattering up to the energy transfer of w = 15 meV using polycrystalline samples. Superconducting samples…
We study the changes in the Fermi surface with electron doping in the LaFeAsO$_{1-x}$F$_x$ superconductors with density-functional supercell calculations using the linearized augmented planewave (LAPW) method. The supercell calculations…
For many years a spin-state transition at $T \approx 100 K$ and insulator - metal transition (IMT) at $T_{IMT} \approx 600 K$ in LaCoO$_3 $ remains a mystery. Small low-spin - high-spin spin gap $\Delta _S = E\left( {HS} \right) - E\left(…
A mean-field theory of the spin Peierls systems based on the two dimensional dimerized Heisenberg model is proposed by introducing an alternating bond order parameter. Improvements with respect to previous mean-field results are found in…
Room temperature Co K- and La L-edges X-ray absorption studies have been carried out on LaCoO$_3$. Experimental near edge structures have been analysed by theoretical LDA+U density of states (DOS) and multiple scattering (MS) calculations.…
Recent experimental work has realized a new insulating state of samarium nickelate (SmNiO$_3$), accessible in a reversible manner via high-density electron doping. To elucidate this behavior, we use the first-principles density functional…
The dynamical spin susceptibility is studied in the magnetically-disordered phase of heavy-Fermion systems near the antiferromagnetic quantum phase transition. In the framework of the $S=1/2$ Kondo lattice model, we introduce a perturbative…
In doped SrTiO$_{3}$ superconductivity persists down to an exceptionally low concentration of mobile electrons. This restricts the relevant energy window and possible pairing scenarios. We present a study of quantum oscillations and…
We systematically investigate the photoexcited (PE) quasi-particle (QP) relaxation and low-energy electronic structure in electron doped Ba(Fe_{1-x}Co_{x})_{2}As_{2} single crystals as a function of Co doping, 0<= x <=0.11. The evolution of…
A detailed investigation of mesoscopic magnetic and crystallographic phase separation in Ca(1-x)La(x)MnO3, 0.00<=x<=0.20, is reported. Neutron powder diffraction and DC-magnetization techniques have been used to isolate the different roles…
Doping dependence of the superconducting state structure and spin-fluctuation pairing mechanism in the $Ba(Fe_{1-x}Co_{x})_{2}As_{2}$ family is studied. BCS-like analysis of experimental data shows that in the overdoped regime, away from…
We demonstrated experimentally a direct way to probe a hidden propensity to the formation of spin density wave (SDW) in a non-magnetic metal with strong Fermi surface nesting. Substituting Fe for a tiny amount of Cu (1%) induced an…
We investigate properties of doping-induced metal-insulator transition in GaN:Si by means of electron spin resonance and Hall effect. While increasing the doping concentration, Si-related bands are formed below the bottom of the GaN…
The SU(2) slave-boson mean-field theory for the tt'J model is analyzed. The role of next-nearest-neighbor hopping t' on the phase-diagram is studied. We find a pseudogap phase in hole-doped materials (where t'<0). The pseudo-gap phase is a…
Quasiparticle properties are explored in an effective theory of the $t-J$ model which includes two important components: spin-charge separation and unrenormalizable phase shift. We show that the phase shift effect indeed causes the system…
The phase diagram of a model describing doped CuGeO$_3$ is derived. The model emphasizes the role of local moments released by the impurities and randomly distributed inside the gaped singlet background. The phase diagram is investigated by…
Using a combination of {\it ab initio} bandstructure methods and dynamical mean-field theory we study the single-particle spectrum of the prototypical charge-transfer insulator NiO. Good agreement with photoemission and…
A semiclassical Monte Carlo approach is adopted to study the multivalley spin depolarization of drifting electrons in a doped n-type GaAs bulk semiconductor, in a wide range of lattice temperature ($40<T_L<300$ K) and doping density…
Only 3% hole doping by Li is sufficient to suppress the long-range antiferromagnetic order in La2CuO4. Spin dynamics in such a disordered state was investigated with measurements of the dynamic magnetic structure factor S(omega,q), using…