Spectral and spatial distribution of polarization at the LaAlO3/SrTiO3 interface
Spectral and spatial distribution of polarization at the LaAlO3/SrTiO3 interface
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DOI：
10.1103/physrevb.83.155405
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发表时间：
2011-04-05
影响因子：
3.7
通讯作者：
Mannhart, J.
中科院分区：
文献类型：
--
作者：
Rubano, A.;Fiebig, M.;Mannhart, J.
利用光学二次谐波产生（SHG）光谱研究了LaAlO3/SrTiO3界面上产生的极化现象。我们的数据显示，当三层LaAlO3外延单层沉积在SrTiO3表面上时，会发生轨道重建。重构表现为LaAlO3/SrTiO3界面上Ti4+(3d)态的光谱修饰，并伴随着相邻SrTiO3单层中Ti4+离子的位移，以补偿界面处引起的极化不连续。根据SHG实验，转移到界面的载流子被困住，因为尽管轨道重建，界面仍然保持绝缘。随着二维电子液体的形成而开始的电导率似乎是与少数载流子有关的从属效应，并且在LaAlO3覆盖率进一步增加时发生。
The polarization induced at the LaAlO3/SrTiO3 interface has been explored by optical second harmonic generation (SHG) spectroscopy. Our data reveal that an orbital reconstruction of the SrTiO3 surface occurs when three epitaxial monolayers of LaAlO3 are deposited on top of it. The reconstruction manifests as a spectral modification of a Ti4+(3d) state at the LaAlO3/SrTiO3 interface which is accompanied by a displacement of the Ti4+ ions in adjacent SrTiO3 monolayers in order to compensate for the polarization discontinuity induced at the interface. According to the SHG experiment, the carriers transferred to the interface are trapped because in spite of the orbital reconstruction, the interface remains insulating. The onset of conductivity with the formation of a two-dimensional electron liquid appears to be a subordinate effect related to a minority of carriers and occurs upon further increase of the LaAlO3 coverage.