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# Optical properties of the spin-ladder compound Sr14Cu24O41

Division of Physics, Lomonosov Moscow State University, Moskva, Moscow, Russia

Physical Review B (Impact Factor: 3.74). 08/2000; 62(8):4963-4972. DOI: 10.1103/PhysRevB.62.4963 Source: arXiv

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Victor V Moshchalkov, May 26, 2014 Available from: Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.

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**ABSTRACT:**We discuss ways in which the ratio of exchange constants along the rungs and legs of a spin-ladder material influences the two-magnon Raman scattering spectra and hence can be determined from it. We show that within the Fleury-Loudon-Elliott approach, the Raman line-shape does not change with polarization geometries. This lineshape is well known to be difficult to calculate accurately from theory. However, the Raman scattering intensities do vary with polarization geometries, which are easy to calculate. With some assumptions about the Raman scattering Hamiltonian, the latter can be used to estimate the ratio of exchange constants. We apply these results to Sugai's recent measurements of Raman scattering from spin-ladder materials such as La$_6$Ca$_8$Cu$_{24}$O$_{41}$ and Sr$_{14}$Cu$_{24}$O$_{41}$. Comment: 5 pages, revtex. Latest version focuses on ladder materials, with a detailed examination of the role of Heisenberg-like coupling constants which appear in the Fleury-Loudon-Elliott scattering operator but are rarely discussed in the literaturePhysical review. B, Condensed matter 04/2000; 62(21). DOI:10.1103/PhysRevB.62.14113 · 3.66 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**We have investigated the electronic structure of the zig-zag ladder (chain) compound SrCuO2 combining polarized optical absorption, reflection, photoreflectance, and pseudo-dielectric-function measurements with the model calculations. These measurements yield an energy gap of 1.42 eV (1.77 eV) at 300 K along (perpendicular to) the Cu-O chains. We have found that the lowest-energy gap, the correlation gap, is temperature independent. The electronic structure of this oxide is calculated using both the local-spin-density approximation with gradient correction method and the tight-binding theory for the correlated electrons. The calculated density of electronic states for noncorrelated and correlated electrons shows quasi-one-dimensional character. The correlation gap values of 1.42 eV (indirect transition) and 1.88 eV (direct transition) have been calculated with the electron hopping parameters t=0.30eV (along a chain), tyz=0.12eV (between chains), and the Anderson-Hubbard repulsion on copper sites U=2.0eV. We concluded that SrCuO2 belongs to the correlated-gap insulators.Physical Review B 01/2001; 63(16). DOI:10.1103/PhysRevB.63.165105 · 3.74 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**We have studied polarized Raman spectra of (TMTSF)2PF6 single crystals in the wide spectral and temperature range using different laser energies. We observed and assigned 23 Raman active modes. The carbon C=C in-phase and out-of-phase stretching modes at 1464 cm-1 and 1602 cm-1 show strong electron-molecular-vibration coupling. The mode at about 1565 cm-1 is temperature independent below 50 K due to the methyl group motion freezing. For (TMTSF)2PF6 in the spin density wave phase for a temperature induced dimensionality 1D (quarter filled dimerized linear chain with correlated electrons) the spin gapless magnon spectra have been calculated. No evidence of spin-lattice coupling or spin-related modes is found in the Raman spectra in the spin density wave phase.Synthetic Metals 05/2001; 124(2-3). DOI:10.1016/S0379-6779(01)00385-X · 2.25 Impact Factor