Colossal Magnetoresistance in La_1-xPb_xMnO₃ Thin Films Prepared by Pulsed Laser Deposition

Abstract

La1-xPbxMnO3 thin films were prepared by off-axis pulsed laser deposition from stoichiometric targets on SrTiO3 and LaAlO3 substrates using KrF excimer laser radiation (248nm). Thin film deposition was performed at substrate temperatures between 650°C and 850°C and an oxygen pressure of 0.4mbar. Thin films prepared at 750°C were single phase and (001)-oriented. Epitaxial film growth was confirmed by x-ray pole figures and RHEED. Magnetic properties were studied by SQUID magnetometry. Ferromagnetic behavior with Curie temperatures between 200°C and 300°C was observed to be dependent on deposition parameters. Magnetoresistance was examined by standard 4-point measurements in fields up to 8T. As an example, a film with Tc = 193K shows a resistance change ((ρ(0)-ρ(H))/ρ(0)) of about 25% at T = 300K. For T = 220K and 180 K the changes are 70%.