Composite polaron mechanism for colossal magnetoresistance in perovskite manganites

The mechanism of carriers accompanied by spin-wave cloud and Jahn–Teller phononic cloud, called composite polaron, is proposed to explain the unusual transport and thermodynamic properties in perovskite manganites over all the temperature and magnetic field range. It is shown that the energy bandwidth of composite polarons is strongly renormalized with the increases of temperature and magnetic field, the bandwidth narrows with elevated temperature, while it broadens with increasing magnetic field. The resistivity of composite polarons increases with elevated temperature strongly, reaches a maximum near the Curie temperature TC, and decreases with the increase of magnetic field. The specific heat of composite polarons also exhibits a maximum near TC. These results agree with experiments in a broad temperature and magnetic field range, suggesting that composite polarons contribute to the unusual properties in manganites.