Switching a Normal Insulator into a Topological Insulator via Electric Field with Application to Phosphorene
Switching a Normal Insulator into a Topological Insulator via Electric Field with Application to Phosphorene
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DOI：
10.1021/nl5043769
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发表时间：
2015-02-01
期刊：
影响因子：
10.8
通讯作者：
Zunger, Alex
中科院分区：
文献类型：
--
作者：
Liu, Qihang;Zhang, Xiuwen;Zunger, Alex
拓扑绝缘体的研究通常涉及寻找具有这种性质的材料，作为一种固有的质量，不同于普通绝缘体。在这里，我们关注的是将普通绝缘体转化为拓扑绝缘体的可能性，通过施加外电场，以不同的能量移动不同的能带，并诱导特定的能带反转，从而导致拓扑状态。磷烯是一种二维（2D）材料，可以通过机械剥离从层状黑磷中分离出来，但与石墨烯和硅烯不同，单层磷烯具有较大的带隙（1.52.2 eV）。因此，表现出带反转和随后的拓扑绝缘体行为是意料之外的。利用第一性原理计算和施加垂直电场f -垂直于几层磷烯，我们预测了从普通绝缘体到拓扑绝缘体并最终到金属的连续转变，作为f -垂直于的函数。拓扑行为随电场的调谐将导致自旋分离的无间隙边缘态，即量子自旋霍尔效应。这一发现开启了通过电场将普通绝缘材料转化为拓扑材料的可能性，并制造出可以同时操纵自旋和电荷载流子的多功能场效应拓扑晶体管。我们利用我们的结果制定了一些设计原则，用于寻找其他可能具有这种电诱导拓扑转变的二维材料。
The study of topological insulators has generally involved search of materials that have this property as an innate quality, distinct from normal insulators. Here we focus on the possibility of converting a normal insulator into a topological one by application of an external electric field that shifts different bands by different energies and induces a specific band inversion, which leads to a topological state. Phosphorene is a two-dimensional (2D) material that can be isolated through mechanical exfoliation from layered black phosphorus, but unlike graphene and silicene, single-layer phosphorene has a large band gap (1.52.2 eV). Thus, it was unsuspected to exhibit band inversion and the ensuing topological insulator behavior. Using first-principles calculations with applied perpendicular electric field F-perpendicular to on few-layer phosphorene we predict a continuous transition from the normal insulator to a topological insulator and eventually to a metal as a function of F-perpendicular to. The tuning of topological behavior with electric field would lead to spin-separated, gapless edge states, that is, quantum spin Hall effect. This finding opens the possibility of converting normal insulating materials into topological ones via electric field and making a multifunctional field effect topological transistor that could manipulate simultaneously both spin and charge carrier. We use our results to formulate some design principles for looking for other 2D materials that could have such an electrical-induced topological transition.