LaAlO3 stoichiometry found key to electron liquid formation at LaAlO3/SrTiO3 interfaces
M. P. Warusawithana, C. Richter, J. A. Mundy, P. Roy, J. Ludwig, S. Paetel, T. Heeg, A. A. Pawlicki, L. F. Kourkoutis, M. Zheng, M. Lee, B. Mulcahy, W. Zander, … 展开作者
M. P. Warusawithana, C. Richter, J. A. Mundy, P. Roy, J. Ludwig, S. Paetel, T. Heeg, A. A. Pawlicki, L. F. Kourkoutis, M. Zheng, M. Lee, B. Mulcahy, W. Zander, Y. Zhu, J. Schubert, J. N. Eckstein, D. A. Muller, C. Stephen Hellberg, J. Mannhart, D. G. Schlom
Emergent phenomena, including superconductivity and magnetism, found in the two-dimensional electron liquid (2-DEL) at the interface between the insulators LaAlO3 and SrTiO3 distinguish this rich system from conventional two-dimensional electron gases at compound semiconductor interfaces. The origin of this 2-DEL, however, is highly debated with focus on the role of defects in the SrTiO3 while the LaAlO3 has been assumed perfect. Our experiments and first principles calculations show that the cation stoichiometry of the nominal LaAlO3 layer is key to 2-DEL formation: only Al-rich LaAlO3 results in a 2-DEL. While extrinsic defects including oxygen deficiency are known to render LaAlO3/SrTiO3 samples conducting, our results show that in the absence of such extrinsic defects, an interface 2-DEL can form. Its origin is consistent with an intrinsic electronic reconstruction occurring to counteract a polarization catastrophe. This work provides a roadmap for identifying other interfaces where emergent behaviors await discovery.
Stoichiometry Dependence of Potential Screening at La$_{(1-δ)}$Al$_{(1+δ)}$O$_3$/SrTiO$_3$ Interfaces
用硬X射线光电子能谱学（HAXPES）和可变动能X射线光电子能谱学（VKE-XPS）对沉积在SrTiO $_3$上的La：Al比为1.1、1.0和0.9的10个晶胞La $_{(1-δ)}$ Al $_{(1+δ)}$ O $_3$薄膜进行了分析。在这三种膜中，已知只有富Al膜具有导电界面。VKE-XPS，再加上最大熵分析，显示富铝，富镧，和化学计量的薄膜之间的组成的深度分布的显着差异;显着的La富集在界面处观察到的富镧和化学计量的薄膜，而富铝显示很少或没有混合。此外，富La和化学计量比的膜在表面处显示出高浓度的Al，这在富Al膜中没有观察到。HAXPES价带（VB）分析表明，相对于化学计量和富镧样品，具有绝缘界面的VB的增宽的富铝样品。这种加宽与横跨富Al膜的电场一致。这些结果与缺陷驱动的电子重构一致。
First principles calculations of band offsets at heterovalent $\varepsilon$-Ge/In$_x$Al$_{1-x}$As interfaces
采用第一性原理电子结构计算方法研究了拉伸应变（001）Ge与（001）In $_{x}$ Al $_{1-x}$ As界面的能带排列.研究了能带偏移对界面结构、界面化学计量比和衬底化学计量比的敏感性。观察到的价带和导带偏移的大的定性变化，包括带偏移类型的变化，表明在实际样品中的带偏移的接口的局部结构变化的重要性。我们的研究结果解释了最近的测量来自XPS核心能级光谱的带偏移的原子穿透通过前几个单层的Ge膜。进行类似的研究，为其他物种的扩散在整个接口，并在一般的频带偏移变化近似线性扩散深度相对于原始的“尖锐”的接口，其中的符号的线性变化取决于扩散的物种的值。能带排列对界面细节的这种大的敏感性表明了通过调整薄膜生长于其上的衬底表面的化学计量来化学控制该IV/III-V族界面的能带偏移的潜在途径。
Atomistic Insights into Cu/amorphous-Ta$_x$N Interfacial Adhesion via Machine Learning Interatomic Potentials: Effects of Stoichiometry and Interface Construction
Atomic-scale Imaging of Iodide-Gold Interactions in Nanoconfined Liquid-Solid Interfaces
Department of Materials, Royal School of Mines, Imperial College London（帝国理工学院皇家矿业学院材料系）；Max Planck Institute for Sustainable Materials（马克斯·普朗克可持续材料研究所）；Univ. Rouen Normandie, INSA Rouen Normandie, CNRS, Groupe de Physique des Matériaux, UMR 6634（鲁昂诺曼底大学，鲁昂诺曼底国立应用科学学院，法国国家科学研究中心，材料物理小组）
