Formation and temperature evolution of correlated polarons in colossal magnetoresistive manganites.

We investigate the temperature dependence of charge ordered clusters in manganites. In terms of an approximate treatment of the half-filled spinless Holstein model incorporating the double exchange effect and nearest-neighbor Coulomb interactions, we find that charge ordering and polaronic states appear simultaneously which naturally defines a correlated polaron state. Without the double exchange, the temperature evolution of the charge (polaron) ordering parameter exhibits a broad peak structure only in the strongly correlated quasiadiabatic regime. Including the double exchange, the peak becomes sharper and is observed both in the quasiadiabatic and antiadiabatic regimes. The peak structure in the quasiadiabatic regime provides an explanation for the temperature dependence of the polaron correlation in nanoscale charge ordered polaron clusters observed in the manganites with intermediate to narrow bandwidths.