Giant magnetoresistive thin films of (La,Pr)(0.7)(Ca,Sr)(0.3)MnO3 prepared by aerosol MOCVD

It has been demonstrated that high quality thin films of Ln(1-x)M(x)MnO(3) can be successfully prepared by aerosol MOCVD at 750 degrees C from volatile thd complexes. Subsequent annealing in oxygen at 750 degrees C is necessary to stabilize the oxygen-content of the films. XRD patterns of the films showed them to be pseudocubic with an apparent lattice parameter linear in the average ionic radius of Ln and M. The evolution of Ln(1-x)M(x)MnO(3) film morphology with increasing the film thickness has also been studied. The morphological instability of the MOCVD process results in the formation of a hillocky surface with thickness > 2000 Angstrom. The electrical properties of La1-xCaxMnO3 and La1-xSrxMnO3 correlate with those reported for bulk and thin film materials. The substitution of Pr for La in La1-xSrxMnO3 reduces the maximum resistivity temperature, T-p, non-linearly. La1-xCaxMnO3 thin films reveal a shift of T-p downwards in the case of substrate materials with a positive lattice mismatch with the films. La0.35Pr0.35Ca0.3MnO3/LaAlO3 demonstrates a very complex temperature dependence of the resistivity, which is described using a conceptual phase diagram of Ln(1-x)M(x)MnO(3). A marked GMR effect was observed for La0.35Pr0.35Ca0.3MnO3/LaAlO3 below 21 K (ca. 10(10)%) and at ca. 70 K even in a field of 1 T.