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Register a new userSpin gap behavior and charge ordering in alpha^{prime}-NaV_2O_5 probed by light scattering
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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$300 K. This system undergoes a phase transition into a singlet ground state at T=34 K accompanied by the formation of a super structure. For T$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$_{4+delta}$.
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