Photo-induced phase separation effect in cuprates

Abstract

Parent insulating cuprates appear to be unstable with regard to a self-trapping of the low-energy one-and two-center CT excitons with a nucleation of electron-hole (EH) droplets being actually the system of coupled electron CuO47- and hole CuO45- centers having been glued in lattice due to strong electron-lattice polarization effects. Such a system can be regarded as an EH Bose liquid described by the generalized Bose-Hubbard Hamiltonian. The scenario can readily explain photo-induced effects in underdoped cuprates. Indeed, illumination of a material with light leads to the generation of EH pairs that will proliferate and grow up to be a novel nonequilibrium EH droplet or simply to be trapped in either EH droplet with the rise in its volume fraction. During the illumination of underdoped cuprate near the insulator-metal transition, the material may even become superconducting. © 2005 IOP Publishing Ltd.