Long-range hopping correlation and colossal magnetoresistance in doped manganites

The nature of the paramagnetic-insulator-to-ferromagnetic-metal transition and the associated colossal magnetoresistance (CMR) in doped manganites is re-investigated on the basis of the double-exchange model by using a Monte Carlo technique. We calculate the temperature dependence of the magnetic su sceptibility and resistivity by taking account of the magnetic fluctuation together with the long-range hopping correlation. The results show Curie-We iss behaviour of the susceptibility, consistent with a sharp peak in the re sistivity near the Curie temperature T-c. The estimated value of T-c and th e magnitude of the CMR in the magnetic field are in good agreement with exp eriments. Our results clearly demonstrate the importance of the magnetic fl uctuation and the long-range hopping correlation in the CMR manganites.