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Spin gap behavior and charge ordering in α^{\prime}-NaV_2O_5 probed by light scattering

M. Fischer·P. Lemmens·G. Els·G. Güntherodt·E. Sherman·E. Morre·C. Geibel·F. Steglich
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Abstract

We present a detailed analysis of light scattering experiments performed on the quarter-filled spin ladder compound $α^\prime$-NaV$_{2}$O$_{5}$ for the temperature range 5 K$\le$T$\le$300 K. This system undergoes a phase transition into a singlet ground state at T=34 K accompanied by the formation of a super structure. For T$\leq$34 K several new modes were detected. Three of these modes are identified as magnetic bound states. Experimental evidence for charge ordering on the V sites is detected as an anomalous shift and splitting of a V-O vibration at 422 cm$^{-1}$ for temperatures above 34 K. The smooth and crossover-like onset of this ordering at T$_{\rm CO}$= 80 K is accompanied by pretransitional fluctuations both in magnetic and phononic Raman scattering. It resembles the effect of stripe order on the super structure intensities in La$_2$NiO$_{4+δ}$.

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M. Fischer, P. Lemmens, G. Els, G. Güntherodt, E. Sherman, E. Morre, C. Geibel, F. Steglich. 1999-07-19. Spin gap behavior and charge ordering in α^{\prime}-NaV_2O_5 probed by light scattering. https://doi.org/10.1103/physrevb.60.7284

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