O.Yu. Gorbenko, A.A. Bosak, A.R. Kaul, N.A. Babushkina, L.M. Belova
The Materials Research Society Proceedings Volume to be published (1998)
ABSTRACT. Thin epitaxial films of (La1-xPrx)0.7Ca0.3MnO3 (x=0,0.25,0.5,0.75,1) were grown on LaAlO3, SrTiO3 and ZrO2(Y2O3) by aerosol MOCVD at 750oC). Variation of x influences greatly the electrical properties of material by change of the tolerance factor t. The tensile strain in the films on perovskite substrates produces the effect on the maximum resistivity temperature Tp comparable with the effect of chemical pressure nearby critical value of t ~ 0.91. By variation of x the colossal magnetoresistance in the very low magnetic field was achieved in the thin films: the field of 0.3 T was enough for 32 times decrease of the resistivity of La0.35Pr0.35Ca0.3MnO3 film on LaAlO3 at 155 K. The charge ordering starting in (La1-xPrx)0.7Ca0.3MnO3 at 160-210 K leads to the switching from Arrhenius law (lg* ~ T-1 ) to Mott law (lg* ~ T-1/4) of resistivity. Large-angle boundaries dominating the structure of the films on ZrO2(Y2O3) increase the resistivity both above and below Tp.