Related papers: Electron-phonon and spin-phonon coupling in NaV$_{…
We investigate the temperature dependent optical properties of NaV2O5, in the energy range 4meV-4eV. The symmetry of the system is discussed on the basis of infrared phonon spectra. By analyzing the optically allowed phonons at temperatures…
We present a detailed analysis of light scattering experiments performed on the quarter-filled spin ladder compound $\alpha^\prime$-NaV$_{2}$O$_{5}$ for the temperature range 5 K$\le$T$\le$300 K. This system undergoes a phase transition…
In the ac polarized Raman spectra of NaV2O5 we have found anomalous phonon broadening, and an energy shift of the low-frequency mode as a function of the temperature. These effects are related to the breaking of translational symmetry,…
We report on a novel spin-charge fluctuation in the all-in-all-out pyrochlore magnet Cd$_2$Os$_2$O$_7$, where the spin fluctuation is driven by the conduction of thermally excited electrons/holes and associated fluctuation of Os valence.…
The electronic structure of two V-based ladder compounds, the quarter-filled NaV$_2$O$_5$ in the symmetric phase and the iso-structural half-filled CaV$_2$O$_5$ is investigated by ab initio calculations. Based on the bandstructure we…
To investigate the possibility whether electron-phonon coupling can enhance orbital fluctuations in iron-based superconductors, we develop an ab initio method to construct the effective low-energy models including the phonon-related terms.…
The effects of spin and charge fluctuations and electron-phonon couplings on charge ordering in \alpha-(BEDT-TTF)_2I_3 (BEDT-TTF=bis(ethylenedithio)-tetrathiafulvalence) are investigated theoretically for an anisotropic triangular lattice…
While 3$d$-containing materials display strong electron correlations, narrow band widths, and robust magnetism, 5$d$ systems are recognized for strong spin-orbit coupling, increased hybridization, and more diffuse orbitals. Combining these…
We argue that in the quarter-filled ladder compound NaV_2O_5 the quasi-one-dimensional spin system is strongly coupled to a low-energy antiferroelectric mode of the excitonic type. This mode results from the interplay between the electron…
The low-temperature electronic and magnetic properties of NH$_4$V$_2$O$_5$, an isoelectronic analog of the spin-ladder compound $\alpha'$-NaV$_2$O$_5$, are investigated using DFT+$U$ calculations. Two charge-ordering patterns - zigzag and…
We investigate the interplay of the electron-phonon and the spin fluctuation interaction for the superconducting state of YBa$_2$Cu$_3$O$_{7}$. The spin fluctuations are described within the nearly antiferromagnetic Fermi liquid theory,…
An investigation of possibilities for superconductivity mediated by spin fluctuations in some elementary metals is motivated by the recent discovery of superconductivity in the hcp high-pressure phase of iron. The electronic structure, the…
The interplay between spin dynamics and lattice vibration has been suggested as an important part of the puzzle of high-temperature superconductivity. Here we report the strong interaction between spin fluctuation and phonon in SmFeAsO, a…
Based on recently proposed anti-ferromagnetic spin fluctuation exchange models for $d_{x^2-y^2}$-superconductors, we show that coupling to harmonic phonons {\it{cannot}} account for the observed isotope effect in the cuprate high-$T_c$…
Raman study on a select few orthochromites, RCrO$_3$ (R = Y, Lu, Gd, Eu and Sm) shows that the phonon behavior at TN in compounds with magnetic R-ion (Gd and Sm) is remarkably different from that of non-magnetic R-ion (Y, Lu and Eu). While…
Polarized Raman and optical spectra for the quasi one-dimensional metallic vanadate beta-Na0.33V2O3 are reported for various temperatures. The spectra are discussed in the light of the sodium and charge ordering transitions occurring in…
Mixed valence spinels provide a fertile playground for the interplay between charge, spin, and orbital degrees of freedom in strongly correlated electrons on a geometrically frustrated lattice. Among them, AlV$_2$O$_4$ and LiV$_2$O$_4$…
We use inelastic neutron scattering to study acoustic phonons and spin excitations in single crystals of NaFeAs, a parent compound of iron pnictide superconductors. NaFeAs exhibits a tetragonal-to-orthorhombic structural transition at…
We argue on the basis of symmetry selection rules and Raman scattering spectra that NaV$_2$O$_5$ undergoes a charge ordering phase transition at T$_c$=34 K. Such a transition is characterized by the redistribution of the charges at the…
The electronic structures, lattice dynamics, and magnetic properties of crystal {\beta}-FeSe under hydrostatic pressure have been studied by using the first-principles electronic structure calculations with van der Waals (vdW) corrections.…