Lim Seongjoon, Kim Jaewook, Won Choongjae, Cheong Sang-Wook
Rutgers Center for Emergent Materials and Department of Physics and Astronomy, Piscataway, New Jersey 08854, United States.
Laboratory for Pohang Emergent Materials, Pohang Accelerator Laboratory and Max Plank POSTECH/KOREA Research Initiative, Pohang University of Science and Technology, Pohang 37673, Korea.
Nano Lett. 2020 Jul 8;20(7):4801-4808. doi: 10.1021/acs.nanolett.0c00539. Epub 2020 Jun 4.
It has been only recently realized that topological vortices associated with structural distortions or ordered spins are rather common in numerous materials where long-range interactions are not dominant. Incommensurate modulations that frequently occur in charge density wave (CDW) materials are often understood in terms of discommensurations with a periodic phase shift. The accumulation of a one-dimensional (1D) phase shift can result in, for example, CDW dislocations in 2H-TaSe with incommensurate CDW (I-CDW). Since any atomic-scale experimental investigation of CDW dislocations in 2H-TaSe has been lacking, we have performed the atomic-scale observation of 2H-TaSe with I-CDW, stabilized with Pd intercalation or strain, with scanning probe microscopy, and unveiled the existence of topological Z or Z vortices with topologically protected 2D winding movements of atomic displacement vectors. The discovery opens the ubiquitous nature of topological vortex domains and a new avenue to explore new facets of various incommensurate modulations or discommensurations.
直到最近才意识到，与结构畸变或有序自旋相关的拓扑涡旋在许多长程相互作用不占主导地位的材料中相当常见。电荷密度波（CDW）材料中经常出现的非公度调制通常根据具有周期性相移的位错来理解。例如，一维（1D）相移的积累会导致具有非公度CDW（I-CDW）的2H-TaSe中出现CDW位错。由于缺乏对2H-TaSe中CDW位错的任何原子尺度实验研究，我们利用扫描探针显微镜对通过钯插层或应变稳定的具有I-CDW的2H-TaSe进行了原子尺度观察，并揭示了具有原子位移矢量拓扑保护二维缠绕运动的拓扑Z或Z涡旋的存在。这一发现揭示了拓扑涡旋域的普遍性质，并为探索各种非公度调制或位错的新方面开辟了一条新途径。
