AVS 62nd International Symposium & Exhibition
    Scanning Probe Microscopy Focus Topic Wednesday Sessions
       Session SP+2D+AS+NS+SS-WeA

Paper SP+2D+AS+NS+SS-WeA4
Chiral Edge States of Topological Insulator in 1D

Wednesday, October 21, 2015, 3:20 pm, Room 212A

Session: Probing Electronic and Transport Properties
Presenter: Tae-Hwan Kim, Pohang University of Science and Technology, Republic of Korea
Authors: T.-H. Kim, Pohang University of Science and Technology, Republic of Korea
S. Cheon, Institute for Basic Science, Republic of Korea
S.-H. Lee, Institute for Basic Science, Republic of Korea
H.W. Yeom, Pohang University of Science and Technology and Institute for Basic Science, Republic of Korea
Correspondent: Click to Email

Chiral edge states are one of the most fascinating hallmark of topological insulators [1-4]. While chiral edge states are the vitally important feature of 2D and 3D topological insulators, no correspondence has yet been found in 1D. On the other hand, in 1D, a Peierls-distorted atomic chain such as polyacetylene has two topologically different ground states and a topological edge state or so-called a topological soliton connecting between them [5,6]. The topological edge states in 1D show many interesting properties such as charge-spin separation, fractional charge, and so on [7,8]. However, they do not exhibit chirality as 2D or 3D topological insulators do. In this talk, we report that the 1D topological edge states, solitons, of the charge-density wave (CDW) system of indium atomic wires self-assembled on a silicon surface have the chiral property [9,10]. Our system can be well described by a coupled double Peierls-distorted atomic chain with zigzag interchain coupling, which induces dynamical sublattice symmetry breaking. This subtle change ensures a dynamically generated topological structure with four-fold symmetric ground states and has topological edge states with a new degree of freedom, chirality, which is absent in the case of a single Peierls atomic chain. We have performed scanning tunneling microscopy and spectroscopy in order to obtain experimental evidences of the chiral edge states in the 1D CDW. Individual right- and left-chiral edge states are directly identified from non-chiral ones, which are similar to the topological solitons found in a single Peierls atomic chain. Furthermore, we found that chiral edge states can produce quantized charge pumping across the chain that is topologically protected and controllable by their chirality. Thus, these topological chiral edge states or solitons can be utilized for future single-electron-level data storage devices or logic circuits, which are topologically protected.

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