相关论文: Raman scattering study of charge ordering in beta-…
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…
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…
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 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…
We report inelastic light scattering studies on Ca(Fe0.97Co0.03)2As2 in a wide spectral range of 120-5200 cm-1 from 5K to 300K, covering the tetragonal to orthorhombic structural transition as well as magnetic transition at Tsm ~ 160K. The…
Temperature dependent optical spectra are reported for beta-Na0.33V2O5. The sodium ordering transition at T_Na = 240 K, and in particular the charge ordering transition at T_MI = 136 K strongly influence the optical spectra. The…
We report an inelastic light scattering study of the effects of charge-ordering on the spin-, charge-, and lattice-dynamics in ${\rm Bi}_{1-x}{\rm Ca}_{x}{\rm MnO}_3$ $(x>0.5)$. We find that charge-ordering results in anomalous phonon…
Charge ordering of V4+ and V5+ in NaV2O5 has been studied by an X-ray diffraction technique using anomalous scattering near a vanadium K-absorption edge to critically enhance a contrast between the two ions. A dramatic energy dependence of…
The polarized Raman scattering spectra from freshly cleaved $ab$, $ac$, and $bc$ surfaces of high quality twin free YBa$_2$Cu$_3$O$_{6.5}$ (Ortho-II) single crystals ($T_c$=57.5 K and $\Delta T = 0.6$ K) were studied between 80 and 300 K.…
Raman scattering experiments have been carried out on single crystals of Nd$_{0.5}$Sr$_{0.5}$MnO$_3$ as a function of temperature in the range of 320-50 K, covering the paramagnetic insulator-ferromagnetc metal transition at 250 K and the…
Polarized Raman scattering and infrared reflection spectra of hexagonal HoMnO$_3$ single crystals in the temperature range 10-300 K are reported. Group-theoretical analysis is performed and scattering selection rules for the second order…
Raman scattering spectra of zigzag spin chain TaFe$_{1.25}$Te$_3$ single crystal are presented in a temperature range from 80 to 300 K. Nine Raman active modes of $A_g$ and $B_g$ symmetry are clearly observed and assigned by probing…
In order to investigate the origin of the phase transition observed in NaV$_2$O$_5$, as well as its electronic structure, we have measured Raman intensities as a function of the laser wavelength above and below the phase transition…
We present the Raman-scattering spectra of CaV2O5 and MgV2O5. The magnetic contribution in the Raman spectra of CaV2O5 is found in the form of a strong asymmetric line, centered at 2Delta, with a tail on the high-energy side. Our analysis…
Inelastic light scattering spectra of several members of the RFe3(BO3)4 family reveal a cascade of phase transitions as a function of temperature, starting with a structural, weakly first order, phase transition followed by two magnetic…
Pb(Mg$_{1/3}$Nb$_{2/3}$)O$_{3}$ is one of the simplest representatives of the class of lead relaxors and often serves as a model system for more complicated compounds. In this paper we analyse both polarized and depolarized Raman scattering…
We have measured far infrared reflectance and transmittance spectra as well as Raman scattering spectra of \alpha'-NaV2O5 single crystals for all the principal polarizations. The temperature range above the phase transition temperature…
We present Raman scattering studies of the structural and magnetic phases that accompany temperature- and field-dependent melting of charge- and orbital-order (COO) in La0.5Ca0.5MnO3 and La0.25Pr0.375Ca0.375MnO3. Our results show that…
We report a detailed Raman scattering study of the lattice dynamics in detwinned single crystals of the underdoped high temperature superconductor YBa2Cu3O6+x (x=0.75, 0.6, 0.55 and 0.45). Whereas at room temperature the phonon spectra of…
We have performed polarized Raman scattering measurements on the newly discovered superconductor Ba$_{2}$Ti$_{2}$Fe$_{2}$As$_{4}$O$_{2}$ ($T_c = 21$ K). We observe seven out of eight Raman active modes, with frequencies in good accordance…