As an important topic of condensed matter physics, metal oxide surfaces often exhibit exotic properties such as high catalytic activity, enhanced ferroelectricity and electronic phase transition, originating from the different local symmetry with respect to the bulk. As the structure determination of oxide surfaces presents challenges to conventional surface science techniques like scanning tunneling microscopy, aberration-corrected transmission electron microscopy (TEM) has been increasingly used to solve structures of oxide surfaces. In this work, the (001) surface of LaAlO₃, one of the most used components of oxide heterostructures, has been investigated. Our TEM experiments and extensive image simulations show that the La-O terminated LaAlO₃(001) surface undergoes significant reconstructions, forming La vacancies on the surface layer. Energetically, the LaAlO₃(001) surface is stable with the reconstructed La-O termination in a wide range of oxygen chemical potentials. Polarity compensation, reduced density of states at the Fermi level and bond enhancement of subsurface oxygen anions all contribute to the stabilization of the reconstructed surface.

作为凝聚态物理的一个重要课题，金属氧化物表面通常表现出奇特的性质，例如高催化活性，增强的铁电性和电子相变，这是由于相对于本体的局部局部对称性不同而引起的。由于氧化物表面的结构确定对诸如扫描隧道显微镜的常规表面科学技术提出了挑战，因此像差校正的透射电子显微镜（TEM）已越来越多地用于解决氧化物表面的结构。在这项工作中，已经研究了LaAlO ₃的（001）表面，这是氧化物异质结构中最常用的成分之一。我们的TEM实验和广泛的图像模拟表明，La-O端接的LaAlO ₃（001）的表面经历显着的重构，在表面层上形成La空位。充满活力的是，LaAlO ₃（001）表面在宽范围的氧化学势中具有经过重建的La-O端接是稳定的。极性补偿，费米能级降低的态密度以及地下氧阴离子的键增强都有助于重建表面的稳定。