Colossal Magnetoresisttve Tffin Films of (La1-x,Prx)0.7Ca0.3MnO3 Prepared by Aerosol MOCVD

Abstract

ABSTRACTThin epitaxial films of (La1-x,Prx)0.7Ca0.3MnO3 (x=0,0.25,0.5,0.75,l) were grown on LaA1O3, SrTiO3 and ZrO2(Y2O3) by aerosol MOCVD at 750°C Variation of x greatly influences the electrical properties of material by changing 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 very low magnetic fields was achieved in the thin films: an applied field of 0.3 T was enough for 32 times decrease of the resistivity of (La0.35,Pr0.35)Ca0.3MnO3 film on LaA1O3 at 155 K. The charge ordering starting in (La1-x,Prx)0.7Ca0.3MnO3 at 160–210 K leads to the switching from Arrhenius law (lggρ ∼ T1 ) to Mott law (lgρ ∼ T1/4) of resistivity. Large-angle boundaries dominating the structure of the films on ZrO2(Y2O3) increase the resistivity both above and below Tp.