Effect of the Substrate Orientation on the Transport Propertiesof La_0.67Sr_0.33MnO₃ Epitaxial Films

The transport properties of La_0.67Sr_0.33MnO₃ (LSMO) epitaxial films on differently orientated LaAlO₃ substrates have been studied. The as-deposited films with different orientation exhibit different transport behaviours. The resistivity of the films on the (100) and (110) substrates undergoes a metal--insulator transition while the resistivity of the film on the (111) substrate is insulator-like. This is attributed to the discrepancy of oxygen deficiency in the samples which is influenced by the lattice mismatch between the film and the substrate. After being annealed at 700°C in 1-atm flowing pure oxygen for half an hour, all films have the same resistivity behaviour as the bulk LSMO, which may be important for future applications.