STATIC AND DYNAMIC CHARGE INHOMOGENEITY AND CRYSTAL-FIELD FLUCTUATIONS FOR 4f IONS IN HIGH-T_c CUPRATES
Moskvin A.S., Panov Yu.D., Mel'nikova N.V.

Received: June 16, 2004

PACS: 74.72.-h, 76.30.Kg, 78.70.Nx

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The main mechanism of inhomogeneous broadening and relaxation of crystal-field excitations for rare-earth ions in cuprates is believed to be provided by the fluctuations of crystalline electric field induced by a static and dynamic charge inhomogeneity generic for the doped cuprates. Such an inhomogeneity is assumed to be a result of topological phase separation. We address the generalized granular model as one of the model scenarios to describe the static and dynamic charge ingomogeneity in cuprates. The charge subsystem is believed to be similar to that of the Wigner crystal with the melting transition and phonon-like positional excitation modes. We consider a simple model of charge inhomogeneity that allows us to elucidate the main universal features of the density of CF states and the respective inhomogeneous broadening. The formal description of R-ion relaxation mainly coincides with that of the recently suggested magnetoelastic mechanism by Lovesey and Staub.