Colossal magnetoresistance of thin films of La0.66Ba0.33MnO3 as a function of film thickness

La0.66Ba0.33MnO3 shows a strong change of its resistivity if a magnetic field is applied. The strength of this colossal magneto resistance (CMR) effect depends of the thickness of epitaxial thin films prepared on MgO (100) and SrTiO3 (100). We have prepared films in a thickness range of 5 to 250 nm by pulsed laser deposition. The epitaxial La0.66Ba0.33MnO3 thin films were characterized by Rutherford backscattering spectrometry and channeling, X-ray diffraction measurements as well as by high resolution transmission electron microscopy (HRTEM). The high crystalline quality was proved by ion channeling (minimum yield of χmin≈2%) and by HRTEM micrographs. By X-ray diffraction measurements, no additional phases were detected beside the cubic phase with a lattice constant a=3.915 Å. The CMR effect of 10 nm thin films is enlarged by 45% as compared to 150 nm thick films on MgO (100) substrates. The saturation magnetization decreases with decreasing film thickness.