Model for strain-induced metal-insulator phase coexistence in colossal magnetoresistive perovskite manganites (invited)

There is considerable evidence from new generations of high resolution microscopies and scattering techniques for intrinsically multiscale structures and dynamics in complex transition-metal oxides. In particular, the coexistence of submicrometer-size insulating and metallic domains in the same sample of perovskite manganites is believed to be crucial to the understanding of colossal magnetoresistance in these materials, and has been a puzzle to both theorists and experimentalists. In this work, we demonstrate, using an atomic-scale description of lattice distortions and long-range strains, that the presence of multiple local energy minimum states with different distortions provides a natural mechanism for such multiphase coexistence within the same material. The framework provides a basis for engineering nanoscale patterns of metallic and insulating phases and understanding other novel features observed in manganites, such as precursor short-range ordering and quasielastic scattering near the phase-transition temperature, hysteretic and glassy dynamics, metastability, and photoinduced insulator-metal transition. (C) 2006 American Institute of Physics.