Effect of oxygen content on the structural, transport, and magnetic properties of La1-delta Mn1-delta O3 thin films

(110) oriented La1-deltaMn1-deltaO3 thin films with different oxygen conten t were grown on (001) LaAlO3 substrates by pulsed laser deposition. Samples prepared in higher oxygen partial pressures show a ferromagnetic transitio n around 200 K. The transport is thermally activated with a change in slope at the ferromagnetic transition. Samples prepared and annealed in vacuum s how signatures of mixed ferromagnetic and antiferromagnetic phases, and are insulators. The pure antiferromagnetic phase (as expected and observed in bulk materials with optimum oxygen stoichiometry) was not obtained in our e xperiments, even in the strongly reduced films. (C) 1999 American Institute of Physics. [S0021-8979(99)02523-2].