New Universal Type of Interface in the Magnetic Insulator/Topological Insulator Heterostructures,Nano Letters

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New Universal Type of Interface in the Magnetic Insulator/Topological Insulator Heterostructures
Nano Letters ( IF 9.6 ) Pub Date : 2018-09-27 00:00:00 , DOI: 10.1021/acs.nanolett.8b03057
Sergey V. Eremeev _{1,

2,

3,

4} , Mikhail M. Otrokov _{2,

3,

5,

6} , Evgueni V. Chulkov _{2,

3,

4,

5}

Affiliation

Magnetic proximity effect at the interface between magnetic and topological insulators (MIs and TIs) is considered to have great potential in spintronics as, in principle, it allows realizing the quantum anomalous Hall and topological magneto-electric effects (QAHE and TME). Although an out-of-plane magnetization induced in a TI by the proximity effect was successfully probed in experiments, first-principles calculations reveal that a strong electrostatic potential mismatch at abrupt MI/TI interfaces creates harmful trivial states rendering both the QAHE and TME unfeasible in practice. Here on the basis of recent progress in formation of planar self-assembled single layer MI/TI heterostructure (T. Hirahara et al. Nano Lett. 2017, 17, 3493–3500), we propose a conceptually new type of the MI/TI interfaces by means of density functional theory calculations. By considering MnSe/Bi₂Se₃, MnTe/Bi₂Te₃, and EuS/Bi₂Se₃ we demonstrate that, instead of a sharp MI/TI interface clearly separating the two subsystems, it is energetically far more favorable to form a built-in interface via insertion of the MI film inside the TI’s surface quintuple layer (e.g., Se–Bi–Se–[MnSe]–Bi–Se) where it forms a bulk-like MI structure. This results in a smooth MI-to-TI connection that yields the interface electronic structure essentially free of trivial states. Our findings open a new direction in studies of the MI/TI interfaces and restore their potential for the QAHE and TME observation.

中文翻译：

电磁绝缘体/拓扑绝缘体异质结构中的新型通用接口

磁性和拓扑绝缘体（MI和TI）之间的界面处的磁性邻近效应被认为在自旋电子学中具有巨大潜力，因为从原理上讲，它可以实现量子异常霍尔效应和拓扑磁电效应（QAHE和TME）。尽管在实验中成功探测到了由邻近效应在TI中感应出的面外磁化强度，但第一性原理计算表明，突然的MI / TI界面处存在严重的静电势不匹配会产生有害的琐碎状态，从而使QAHE和TME均不可行在实践中。这里的最新进展在形成平面的自组装单层MI / TI异质结构（T. Hirahara等人的基础上纳米快报。 2017年，17（3493–3500），我们通过密度泛函理论计算提出了一种概念上新型的MI / TI接口。通过考虑MnSe / Bi ₂ Se ₃，MnTe / Bi ₂ Te ₃和EuS / Bi ₂ Se ₃我们证明，与其通过清晰的MI / TI界面清楚地将两个子系统分隔开来，不如通过在TI的表面五元层（例如Se–Bi– Se- [MnSe] -Bi-Se）形成块状MI结构。这导致平滑的MI-TI连接，从而产生基本上没有琐碎状态的接口电子结构。我们的发现为MI / TI接口的研究开辟了新的方向，并恢复了它们在QAHE和TME观测中的潜力。

更新日期：2018-09-27

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