Colossal magnetoresistance in potassium doped lanthanum manganite: A comparative study of polycrystalline solid and thin film

Electrical and magnetic properties of La0.82K0.08MnO3-delta, both in polycr ystalline and thin film forms, have been examined in the temperature range 1.2 to 300 K. Near the insulator-to-metal transition temperature of 260 K, the magnetoresistance values were higher for the thin film (similar to 70%) compared to the polycrystalline sample (similar to 35%). No magnetoresistan ce,vas observed in the thin film at low temperature. A low field magnetores istance of 30% was observed in the temperature range 1.2-10 K in the polycr ystalline sample which can be attributed to the spin dependent scattering o f conduction electrons at the grain boundaries. (C) 1999 Academic Press.