标题： 外延 La0.7Sr0.3MnO3-δ 薄膜在氧捕获辅助热退火作用下发生的拓位相变 显示英文标题

标题： Topotactic phase transition in epitaxial La0.7Sr0.3MnO3-δ films induced by oxygen getter assisted thermal annealing

摘要： 氧空位在控制复杂氧化物的物理性质中起着关键作用。 在La0.7Sr0.3MnO3-{\delta }中，可以通过热退火过程中去除氧气引发从钙钛矿（PV）到布朗米特（BM）的拓扑相变。 在这里，我们报告了一种使用铝作为氧捕获材料的高效热真空退火方法。 通过X射线衍射对拓扑相变进行表征，证实了通过物理气相沉积生长的La0.7Sr0.3MnO3-{\delta }薄膜成功地从PV转变为BM。 该方法的效率通过La0.7Sr0.3MnO3-{\delta }微米级块状粉末得到确认。 伴随的原始铁磁（FM）状态向反铁磁（AF）状态的转变以及金属态向绝缘态的同时转变分别通过超导量子干涉器件（SQUID）磁强计和交流（AC）电阻率测量进行表征。 近表面的锰氧化状态通过同步辐射X射线吸收光谱进行探测。 此外，X射线反射率、原子力显微镜和扫描透射电子显微镜揭示了在氧捕获辅助退火过程中表面偏析和阳离子再分布。 显示英文摘要

摘要： Oxygen vacancies play a crucial role in controlling the physical properties of complex oxides. In La0.7Sr0.3MnO3-{\delta}, the topotactic phase transition from Perovskite (PV) to Brownmillerite (BM) can be triggered e.g. via oxygen removal during thermal annealing. Here we report on a very efficient thermal vacuum annealing method using aluminum as an oxygen getter material. The topotactic phase transition is characterized by X-ray Diffraction which confirms a successful transition from PV to BM in La0.7Sr0.3MnO3-{\delta} thin films grown via physical vapor deposition. The efficiency of this method is confirmed using La0.7Sr0.3MnO3-{\delta} micron-sized bulk powder. The accompanying transition from the original Ferromagnetic (FM) to an Antiferromagnetic (AF) state and the simultaneous transition from a metallic to an insulating state is characterized using Superconducting Quantum Interference Device (SQUID)-magnetometry and Alternating Current (AC) resistivity measurements, respectively. The near surface manganese oxidation states are probed by synchrotron X-ray Absorption Spectroscopy. Moreover, X-ray Reflectivity, Atomic Force Microscopy and Scanning Transmission Electron Microscopy reveal surface segregation and cation redistribution during the oxygen getter assisted annealing process.