Zhao Fangzhou, Cao Ting, Louie Steven G
Department of Physics, University of California at Berkeley, Berkeley, California 94720, USA.
Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA.
Phys Rev Lett. 2021 Oct 15;127(16):166401. doi: 10.1103/PhysRevLett.127.166401.
Graphene nanoribbons (GNRs) possess distinct symmetry-protected topological phases. We show, through first-principles calculations, that by applying an experimentally accessible transverse electric field, certain boron and nitrogen periodically codoped GNRs have tunable topological phases. The tunability arises from a field-induced band inversion due to an opposite response of the conduction- and valence-band states to the electric field. With a spatially varying applied field, segments of GNRs of distinct topological phases are created, resulting in a field-programmable array of topological junction states, each may be occupied with charge or spin. Our findings not only show that electric field may be used as an easy tuning knob for topological phases in quasi-one-dimensional systems, but also provide new design principles for future GNR-based quantum electronic devices through their topological characters.
石墨烯纳米带（GNRs）具有独特的对称性保护拓扑相。我们通过第一性原理计算表明，通过施加实验上可实现的横向电场，某些硼和氮周期性共掺杂的GNRs具有可调控的拓扑相。这种可调性源于电场诱导的能带反转，这是由于导带和价带状态对电场的相反响应所致。随着空间变化的外加电场，会产生不同拓扑相的GNRs段，从而形成一个电场可编程的拓扑结态阵列，每个结态都可以被电荷或自旋占据。我们的发现不仅表明电场可以用作准一维系统中拓扑相的简易调节旋钮，还通过其拓扑特性为未来基于GNR的量子电子器件提供了新的设计原则。
