Seminars & Lectures
| * TITLE | Unexpected two-dimensional chiral orders in one-dimensional charge-density waves | ||||||
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| * DATE / TIME | 2020-07-01, 10:00-11:00 | ||||||
| * PLACE | #503, Hogil Kim Memorial Bldg. & ZOOM Webinar | ||||||
| * ABSTRACT | |||||||
| Chirality or handedness manifests in various forms in nature and plays a significant role in all branches of the natural sciences including chemistry, biology, mathematics, and physics. For example, in spin-ordered states, chirality manifests magnetic chiral solitons in chiral magnets, vortexes or skyrmions in thin magnetic layers, and topological monopoles in Weyl semimetals. Such richness is quite natural because of the vector order parameter in spin systems. Although 1T-TiSe2 was proposed as the first charge-density wave (CDW) system with a real-space chiral stacking order due to inversion symmetry breaking, a recent work reported that the remaining inversion symmetry with CDW contradicts the proposed existence of the chiral CDW stacking order. Thus, there is no compelling evidence of the chirality in charge-ordered states due to their scalar order parameters. Recently, topological solitons with chirality are realized in quasi-one-dimensional (quasi-1D) CDW atomic wires consisting of indium atoms on Si(111). Even though the solitons are found to exhibit unusual topological properties, their CDW groundstates have not been explored in terms of chirality or chiral order. In this work, we have explored the chirality among quasi-1D CDW ground states with scanning tunneling microscopy, symmetry analysis, and density functional theory calculations. We discovered three distinct chiralities emerging in the form of two-dimensional chiral stacking orders composed of degenerate CDW ground states. Such chiral stacking orders correspond to newly introduced chiral winding numbers. Furthermore, we observed that these chiral stacking orders are intertwined with chiral vortexes and chiral domain walls, which play a crucial role in engineering the chiral stacking orders. Our findings suggest that the unexpected chiral stacking orders can open a new way to investigate the chirality in CDW systems, which can lead to diverse phenomena on chirality. ■ On-site You can participate in the lecture series directly on-site at seminar room #503 of the Center. ■ ZOOM Webinar 1) Click the following link https://zoom.us/j/94303918634?pwd=SU95bXpHSFhqLzcyNkMzNDk1U0h3dz09 2) Join the webinar with your email account and name |
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