双层锰氧化物薄膜的制备及其物理性质

The preparation and properties of bilayer manganite films

用脉冲激光沉积 (PLD)方法成功地制备了双层钙钛矿结构的La2 - 2xSr1 + 2xMn2 O7(x =0 32 )单相薄膜 .这种薄膜生长在具有不同晶格参数的两种衬底上 .测量发现 ,两种衬底上生长的La2 - 2xSr1 + 2xMn2 O7(x =0 32 )薄膜具有迥然不同的金属 绝缘体转变温度TM -I及其他物性 .界面应力的研究表明这是衬底晶格常数不同引起膜内应变的结果 .在衬底的压应力下 ,薄膜的电阻 温度曲线的峰值 (TM -I)向高温移动且电阻率 (ρ)下降 ;相反 ,对于衬底张应力下的薄膜 ,TM -I下降 ρ上升 .这些结果可以用双交换模型做很好的解释 .

The bilayer manganite film La2-2x Sr1 + 2x Mn2O7 ( x = 0.32) were successfully prepared by pulsed laser deposit ion (PLD) method. By controlling the parameters of deposition, tire 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( TM - 1) 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 tire above observations. Tensile strain decreases TM - 1 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.