2016年1月14日（周四）上午10:00，量子物質科學協同創新中心 & 物理系seminar：

報告題目： Z4 Topology and Chiral Solitons of Atomic Wires for Topological Informatics 報告人： Han Woong Yeom Center for Artificial Low Dimensional Electronic Systems, Institute for Basic Science, Pohang, Korea Department of Physics, POSTECH, Pohang, Korea 報告時間： 2016-1-14 10:00am 報告地點：理科樓三樓報告廳（C302）摘要： Self-assembled atomic wires have attracted substantial interest in last decade due to their potential to reveal new physics of 1D electrons and as possible components of atomic scale device architecture. A few interesting issues have been discussed so far such as charge density waves (CDW), non-Fermi liquid behavior, and giant Rashba splitting. In this talk, I will review our recent work on the topological nature of indium atomic wires on Si(111) in its CDW ground state [1], which lead us to new topological physics. In this well known system, we recently succeeded in directly observing individual soliton excitations within its CDW band gap [2]. It has been known that 1D Peierls chains are 1D topological insulators and solitons are their edge states protected topologically. Each indium atomic wire on Si(111) is composed of double Peierls chains, which yield uniquely four, not two, degenerate ground states. This fourfold degeneracy corresponds to the first materials realization of a Z4 topological insulator as revealed its band structure [3]. In turn, this unique topology brings about three distinct soliton edge states within the band gap as clearly observed in scanning tunneling microscopy and spectroscopy [4]. These solitons are endowed with chirality, which corresponds to the chiral edge current of higher dimensional topological insulators [4]. We thus for the first time clarify the 1D chiral edge state of a 1D topological insulator. The exciting prospect of utilizing chiral solitons for the topologically-protected multi-level informatics, which I would call ‘chiral solitonics,’ is introduced.
REFERENCES
1. Tae-Hwan Kim and Han Woong Yeom, Phys. Rev. Lett. 109, 246802 (2012).
2. Han Woong Yeom et al., Phys. Rev. Lett. 82, 4898 (1999).
3. J. R. Ahn, J. H. Byun, H. Koh, E. Rotenberg, S. D. Kevan, and H. W. Yeom, Phys. Rev. Lett. 93, 106401 (2004).
4. Sang-Mo Chun, Sung Hoon Lee, Tae-Hwan Ki, and Han Woong Yeom, Science, 350, 182 (2015).