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首页> 外文会议>Symposium on Multicomponent Oxide Films for Electronics held April 6-8,1999,San francisco,California,U.S.A. >Influence of post-deposition annealing on lattice strain, electrical transport and magnetic properties in epitaxial La_0.8Ca_0.2MnO_3 CMR films
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Influence of post-deposition annealing on lattice strain, electrical transport and magnetic properties in epitaxial La_0.8Ca_0.2MnO_3 CMR films

机译：沉积后退火对外延La_0.8Ca_0.2MnO_3 CMR薄膜晶格应变，电输运和磁性能的影响

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摘要

The effect of annealing on 3-dimensional lattice strain, crystallographic domain structure, magnetic and electricla properties of both 250 A and 4000 A thick epitaxial La_0.8Ca_0.2MnO_3 (LCMO(X=0.2)) thin films grown on (001) LaAlO_3 substrates have been studied. While short annealing time (approx 2hrs. at 950 deg C in oxygen of 1 atm. pressure) leads to anomalous increase of the peak temperature (T_p) and Curie temperature (T_c) above room temperature and that of the bulk material, longer annealing time (approx 10 hrs)restores the T_p and T_c to almost the same values as that of the as-grown films. Furthermore, as the annelaing time is increased, the lattice strain relaxes with film's lattice parameter approaching the bulk value. In-plane and out-of-plane lattice parameters and strain states of the as-grown and annealed films were measured directly using normal and grazing incidence x-ray diffraction. a clear correlation is observed between T_p and perovskite unit cell volume for both the films. T_p is found to increase with the decrease of perovskite unit cell volume. This is attributed to the enhancement of overlap between Mn d orbitals and oxygen p orbitals leading to increased bandwidth and conductivity. Crystalline quality of the films as determined by the full width at half maximum (FWHM) of the x-ray rocking curves. improves with the annealing time. This work highlights the importance of controlling the 3-improves with the annealing time. This work highlights the improtance of controlling the 3-dimensional lattice strain for optimizing the properties of CMR films.
机译：退火对在（001）LaAlO_3衬底上生长的250 A和4000 A厚外延La_0.8Ca_0.2MnO_3（LCMO（X = 0.2））薄膜的3维晶格应变，晶体畴结构，磁电性质的影响已经研究过了。虽然退火时间短（在1个大气压的氧气中在950摄氏度下大约2小时）会导致峰值温度（T_p）和居里温度（T_c）高于室温以及散装材料的异常升高，但退火时间更长（大约10个小时）将T_p和T_c恢复为与新胶片几乎相同的值。此外，随着退火时间的增加，晶格应变随着薄膜的晶格参数接近整体值而松弛。使用法向和掠入射x射线衍射直接测量生长和退火薄膜的面内和面外晶格参数以及应变状态。对于两种膜，在T_p和钙钛矿晶胞体积之间观察到明显的相关性。发现T_p随着钙钛矿晶胞体积的减少而增加。这归因于Mn d轨道和氧p轨道之间重叠的增强，导致带宽和电导率增加。薄膜的晶体质量由X射线摇摆曲线的半峰全宽（FWHM）决定。随着退火时间的增加。这项工作强调了控制退火时间与3改进的重要性。这项工作凸显了控制3维晶格应变以优化CMR膜性能的重要性。

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