Inherent inhomogeneity in two-component model for cuprates

Numerous experimental results indicate that the low temperature state of cuprates possesses an inherent inhomogeneity caused by the tendency for electronic phase separation in cuprates at doping. The tendency is discussed in terms of the two-component model (Gor'kov and Sokol, JETP Lett. 46,420 (1987)) where the phenomenon has been predicted to exist. Phase segregation results in the formation of domains whose sizes are limited by the electroneutrality condition. We discuss the Coulomb effects and consider possible mechanisms regulating scales of the spatial and time fluctuations in the system. Electronic phase separation being a general phenomenon and inherent to practically any short-ranged model interaction, we speculate that the so-called "precursor" (or pseudogap) feature at T* may be due to onset of such a regime of inhomogeneous phases' coexistence and is not related synonymously to the appearance of preformed Cooper pairs. We also touch an issue of large isotope effects observed recently in a number of the normal cuprates' characteristics and suggest a qualitative justification of these views.