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Raman Scattering in the Inorganic Spin-Peierls System alpha'-Na_{1-delta}V_2O_5

H. Kuroe·H. Seto·J. Sasaki·T. Sekine·M. Isobe·Y. Ueda
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Abstract

We have studied the spin-Peierls (SP) transition in alpha'-Na_{1-delta}V_2O_5 (delta = 0, 0.01 and 0.1) by means of Raman scattering. At room temperature, we observe six A_1 and three A_2 phonon modes and a broad Raman band. Below T_{SP}several new peaks and a new broad band appear. The new peak at 62 cm^{-1} originates from the SP-gap excitation. The new peak at 128 cm^{-1} and the new broad band between 130 and 400 cm^{-1} come from two magnetic excitations. The new peaks at 102, 646 and 944 cm^{-1} are assigned to the folded phonon modes and their Na^+-ion deficiency dependence shows that the defect of Na^+ ion suppresses the SPtransition. The polarized Raman spectra below T_{SP} suggest that the possible crystal symmetry is C_s^2(Pn) or C_1^1(P1). The asymmetric lineshape of the 531-cm^{-1} peak superimposed on the electronic Raman band from the d-d transition around 600 cm^{-1} is interpreted in terms of the Fano resonance between the electronic continuous band and the phonon with a finite lifetime. The defects of the Na^+ ions reduce the Fano effect because the life time of the phonon and the phonon-continuum interaction are decreased.

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H. Kuroe, H. Seto, J. Sasaki, T. Sekine, M. Isobe, Y. Ueda. 1998-05-20. Raman Scattering in the Inorganic Spin-Peierls System alpha'-Na_{1-delta}V_2O_5. https://doi.org/10.1143/jpsj.67.2881

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