The preparation and properties of bilayer manganite films
双层锰氧化物薄膜的制备及其物理性质

The bilayer manganite film La 2-2 x Sr 1+ 2x Mn 2O 7( x =0 32)were successfully prepared by pulsed laser deposition(PLD)method.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.After measurements of transport property,it is found that there is 80K deference between the two cusp temperatures in resistivity temperature curves( T M-I ) of the two films grown on SrTiO(001) and NdGaO(110).At the same time,the resistivity of the film on SrTiO(001)is 50 times higher than that of the film on NdGaO(110).We studied the influence of the interface strain and found that the lattice mismatch between substate and film is the main reason of the above observations.Tensile strain decreases T M-I with increasing resistivity and compressed strain has an opposite effect.Using double exchange model by Zener,we found that these results can be explained qualitatively.