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arXiv 0901.4610cond-mat.str-elcond-mat.mtrl-sci
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SrTiO3和LaAlO3界面的结构弛豫和金属-绝缘体转变

Structural relaxation and metal-insulator transition at the interface between SrTiO3 and LaAlO3

Natalia Pavlenko, Thilo Kopp

摘要:

采用局域自旋密度近似(LSDA+U)方法研究了LaAlO $_3$和SrTiO $_3$界面的电子结构.我们发现,界面金属态的性质是强烈的影响的类型的结构(三明治或双层)和终止表面的LaAlO $_3$。在所有结构中,原子弛豫对系统的电子性质起着至关重要的作用。虽然在夹层结构中,结构弛豫在SrTiO $_3$中产生显著的极化,并且在Ti $3d_{xy}$轨道的Jahn-Teller样分裂中产生显著的极化,但是在AlO $_2$封端的双层结构中,弛豫主要发生在LaAlO $_3$中,并且导致随着LaAlO $_3$层的厚度增加而在实验中观察到的绝缘体-金属转变。

英文摘要:

The electronic structure of interfaces between LaAlO$_3$ and SrTiO$_3$ is studied using local spin density approximation (LSDA) with intra-atomic Coulomb repulsion (LSDA+U). We find that the nature of the interface metallic states is strongly affected by the type of the structure (sandwich or bilayer) and by the termination surface of LaAlO$_3$. In all structures the atomic relaxation plays a crucial role in the electronic properties of the system. While in sandwiches the structural relaxation produces a significant polarization in SrTiO$_3$ and Jahn-Teller like splitting of Ti $3d_{xy}$ orbitals, in AlO$_2$-terminated bilayers the relaxation occurs primarily in LaAlO$_3$ and results in an insulator-metal transition which has been observed experimentally with increasing thickness of the LaAlO$_3$ layer.

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