Magnetoresistance and magnetic properties of La_1-x□_xMnO_3-δ thin films

Epitaxial thin films of La1-x□xMnO3-δ(0≤x□0≤0.33) where □ is a vacancy have been grown on (100) SrTiO3 substrates by pulsed laser deposition. The lanthanum deficiency results in self doping of the system without the need for divalent ion substitution. Both the films and the bulk targets used for deposition were ferromagnetic and showed giant magnetoresistance (GMR). The films increased in saturation magnetization Ms and Curie temperature Tc with increasing x. The Tc, however, was about the same as found in Cax substitutions. Bulk samples showed little change in Ms and Tc with vacancy concentration. MS in bulk samples is about half the value found in the films which have theoretical saturations for x>0.2. GMR in the films is a few hundred percent but the bulk values are 25% at H = 1.8 T. © 1996 American Institute of Physics.