Grain Size Dependent Transport and Magnetoresistance Behavior of Chemical Solution Deposition Grown Nanostructured La07Sr03MnO3 Manganite Films

Grain-size dependence of electronic transport and magnetoresistance (MR) properties of nanostructured La0.7Sr0.3 MnO3 (LSMO) manganite thin films on LaAlO3 (100) single crystal substrates prepared using Chemical Solution Deposition (CSD) technique have been studied. The LSMO thin films were annealed at temperatures in the range of 700–1000 °C for different time intervals [6 h and 12 h] and crystallized as singlephase LSMO. Microstructural studies carried out using AFM show a marginal increase in the grain-size from 50 to 90 nm as the temperature was varied from 700 °C to 1000 °C respectively. It has been observed that the insulator-metal transition (TP) and MR depend on the grain size. In zero applied field, resistivity reduction is ∼ 103 at 5 K for the films annealed at 700 °C [TP ∼ 341 K] and 1000 °C [TP ∼ 373 K]. MR versus H isotherms reveal that MR enhances in the vicinity of TP but decreases at low temperatures. The results obtained from the electronic and magnetotransport studies are in good agreement with the change in surface morphology of the films studied, which shows that the randomly distributed domains are composed of faceted grains. Synthesizing conditions, annealing temperature and time control the growth and alignment of grains into the domains, which cause better conduction at grain interface.