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要旨:
Raman experiments on the Spin-Peierls compound CuGeO(3) and the
substituted (Cu(1-x),Zn(x))GeO(3) and Cu(Ge(1-x),Ga(x))O(3) compounds
were performed in order to investigate the response of specific magnetic
excitations of the one-dimensional spin-chain to spin anisotropies and
substitution-induced disorder. In pure CuGeO(3), in addition to normal
phonon scattering which is not affected at all by the spin-peierls
transition, four types of magnetic scattering features were observed.
Below T(SP) = 14 K a singlet-triplet excitation at 30 cm(-1), two-magnon
scattering from 30 to 227 cm(-1) and folded phonon modes at 369 and 819
cm(-1) were identified. They were assigned by their temperature
dependence and lineshape. For temperatures between the spin-peierls
transition T(SP) and approximately 100 K a broad intensity maximum
centered at 300 cm(-1) is observed. The temperature dependence of this
intensity is similar to the behavior of lattice fluctuations recently
observed in an electron diffraction study. This scattering is attributed
to dynamical spin-peierls fluctuations of the weakly or non-static
dimerized spin chain.
