Preparation and properties of bilayer manganite films

A bilayer manganite film La2-2xSr1+2xMn2O7 (x=0.32) was successfully prepared by pulsed laser deposition. By controlling the parameters of deposition, the fabricated films are of single phase and grown well on two kinds of substrates with different lattice constants. It is found that there is 80 deg. K difference between TMI of the two films grown on SrTiO (0 0 1) and NdGaO (1 1 0). At the same time, the resistivity of the film on SrTiO (0 0 1) is 50 times higher than that of the film on NdGaO (1 1 0). We studied the influence of the interface strain and it turns out that the lattice mismatch between substrate and film is the main reason for the above observations. Tensile strain decreases TMI with increasing resistivity, and compressive strain has the opposite effect. Using the double-exchange model of Zener, these results can be explained qualitatively