TRANSPORT-PROPERTIES AND COLOSSAL MAGNETORESISTANCE IN EPITAXIAL LA0.67CD0.33MNO3 THIN-FILM

An optimal composition of La0.67Cd0.33MnO3 was synthesized by ceramic route. The compound crystallized in a rhombohedral structure with latt ice parameters a = 5.473(4) Angstrom and alpha = 60 degrees 37' Resist ivity measurement showed an insulator-to-metal transition coupled with a ferromagnetic transition of around 255 K. Epitaxial thin films were fabricated on the LaAlO3 (100) substrate by a pulsed laser deposition technique. The psuedocubic lattice parameter a of the film is 3.873(4 ) Angstrom. The insulator-to-metal transition of the film was observed at 250 K which is comparable with the bulk value. The film was ferrom agnetic below this temperature. Magnetoresistance defined as Delta R/R -0 = (R-H-R-0)/R-0 was over -86% near the insulator-to-metal transitio n temperature of 240 K at 6 T magnetic field and over-30% at relativel y low fields of 1 T. No magnetoresistance was observed at low temperat ures in the film unlike in the polycrystalline sample, where about a 4 0% decrease in resistance was observed on applying 6 T magnetic field due to the spin dependent scattering at the grain boundaries. (C) 1997 American Institute of Physics. [S0003-6951(97)02344-9].