DFT + DMFT的CaVO $_3$薄膜与SrTiO $_3$和LaAlO $_3$的多层工程
Multilayer engineering of CaVO$_3$ thin films with SrTiO$_3$ and LaAlO$_3$ from DFT+DMFT
摘要：
本文采用密度泛函理论结合动力学平均场理论（DFT+DMFT）研究了关联金属CaVO $_3$薄膜与两种典型衬底材料SrTiO $_3$和LaAlO $_3$之间的界面效应。我们发现，CaVO $_3$ /SrTiO $_3$界面上的CaVO $_3$薄膜只有一个边际的影响，与占主导地位的效果是（bulklike）的外延应变所施加的大晶格失配，使CaVO $_3$膜绝缘由于增强的轨道极化与强的水平分裂之间的t $_{\mathrm{2g}}$轨道。相反，在极性CaVO $_3$ /LaAlO $_3$界面处，界面的存在可以对薄膜性质具有巨大影响，这取决于特定界面终止以及由多层几何形状施加的特定边界条件。我们比较了三种不同的方法来模拟相关的金属CaVO $_3$和带绝缘体LaAlO $_3$，这都施加了一组不同的（静电）边界条件的电子结构之间的接口。从我们的计算得到的光谱特性揭示了强烈的影响的超晶胞几何形状，从散装高度掺杂和结构扭曲的阶段，表明通过多层工程的界面特性的潜在可调性。
英文摘要：
In this paper we use density functional theory combined with dynamical mean-field theory (DFT+DMFT) to study interface effects between thin films of the correlated metal CaVO$_3$ and the two typical substrate materials SrTiO$_3$ and LaAlO$_3$. We find that the CaVO$_3$/SrTiO$_3$ interface has only a marginal influence on the CaVO$_3$ thin film, with the dominant effect being the (bulklike) epitaxial strain imposed by the large lattice mismatch, rendering the CaVO$_3$ film insulating due to the enhanced orbital polarization related to the strong level splitting between the t$_{\mathrm{2g}}$ orbitals. In contrast, at the polar CaVO$_3$/LaAlO$_3$ interface, the presence of the interface can have a huge effect on the thin film properties, depending both on the specific interface termination as well as the specific boundary conditions imposed by the multilayer geometry. We compare three different approaches to model the interface between the correlated metal CaVO$_3$ and the band insulator LaAlO$_3$, which all impose a different set of (electrostatic) boundary conditions on the electronic structure. The spectral properties obtained from our calculations reveal a strong influence of the supercell geometry, ranging from bulklike to highly doped and structurally distorted phases, indicating a potential tunability of the interfacial properties via multilayer engineering.
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