International Center for Quantum and Molecular Structures, Physics Department, Shanghai University, Shanghai, 200444, China.
Materials Genome Institute and Shanghai Key Laboratory of High Temperature Superconductors, Shanghai University, Shanghai, 200444, China.
Sci Rep. 2018 Jan 11;8(1):467. doi: 10.1038/s41598-017-18858-x.
We explored the possibility of increasing the interfacial carrier quantum confinement, mobility and conductivity in the (LaAlO)/(BaTiO) superlattices by thickness regulation using the first-principles electronic structure calculations. Through constructing two different interfacial types of LaAlO/BaTiO superlattices, we discovered that the LaO/TiO interface is preferred from cleavage energy consideration. We then studied the electronic characteristics of two-dimensional electron gas (2DEG) produced at the LaO/TiO interface in the LaAlO/BaTiO superlattices via spin-polarized density functional theory calculations. The charge carrier density of 2DEG has a magnitude of 10 cm (larger than the traditional system LaAlO/SrTiO), which is mainly provided by the interfacial Ti 3d orbitals when the thicknesses of LaAlO and BaTiO layers are over 4.5 unit cells. We have also revealed the interfacial electronic characteristics of the LaAlO/BaTiO system, by showing the completely spin-polarized 2DEG mostly confined at the superlattice interface. The interfacial charge carrier mobility and conductivity are found to be converged beyond the critical thickness. Therefore, we can regulate the interfacial confinement for the spin-polarized 2DEG and quantum transport properties in LaAlO/BaTiO superlattice via controlling the thicknesses of the LaAlO and BaTiO layers.
我们通过使用第一性原理电子结构计算来探索通过厚度调节增加（LaAlO）/（BaTiO）超晶格中界面载流子量子限制、迁移率和电导率的可能性。通过构建两种不同的 LaAlO/BaTiO 超晶格界面类型，我们发现从解理能的角度考虑，LaO/TiO 界面是优选的。然后，我们通过自旋极化密度泛函理论计算研究了 LaAlO/BaTiO 超晶格中 LaO/TiO 界面处产生的二维电子气（2DEG）的电子特性。2DEG 的电荷载流子密度为 10 cm（大于传统系统 LaAlO/SrTiO），当 LaAlO 和 BaTiO 层的厚度超过 4.5 个单位时，主要由界面 Ti 3d 轨道提供。我们还通过显示完全自旋极化的 2DEG 主要局限在超晶格界面，揭示了 LaAlO/BaTiO 系统的界面电子特性。发现界面载流子迁移率和电导率在临界厚度之后趋于收敛。因此，我们可以通过控制 LaAlO 和 BaTiO 层的厚度来调节 LaAlO/BaTiO 超晶格中自旋极化 2DEG 的界面限制和量子输运性质。
