Charge-ordering phase transition and order-disorder effects in the Raman spectra of NaV2O5

Abstract

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, caused by electrical disorder that originates from the fluctuating nature of the V {4.5+} valence state of vanadium. The structural correlation length, obtained from comparisons between the measured and calculated Raman scattering spectra, diverges at T< 5 K, indicating the existence of the long-range charge order at very low temperatures, probably at T=0 K.

8 pages, 4 figures, new version, to appear in PRB

References in corpus (13)

• NaV_2O_5 as a quarter-filled ladder compound
• Experimental evidence for a spin-Peierls-transition in ${\alpha }^{\prime }-Na{V}_2{O}_5$
• Charged Magnons in NaV2O5
• Charge ordering and spin- Peierls transition in alpha'-NaV2O5
• Anomalous thermal conductivity of NaV2O5 as compared to conventional spin-Peierls system CuGeO3
• Magnon splitting induced by charge ordering in NaV_2O_5
• Charge Order Driven spin-Peierls Transition in NaV2O5
• Spin gap behavior and charge ordering in α^{\prime}-NaV_2O_5 probed by light scattering
• Elastic Constants and Charge Ordering in a'-NaV2O5
• Charge Order in NaV2O5 studied by EPR
• Raman Scattering in the Inorganic Spin-Peierls System alpha'-Na_{1-delta}V_2O_5
• First evidence for charge ordering in NaV${}_2$O${}_5$ from Raman spectroscopy
• Spin-Peierls transition in NaV2O5 in high magnetic fields