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セガワ コウジ
SEGAWA KOJI
瀬川 耕司 所属 京都産業大学 理学部 物理科学科 職種 教授 |
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| 言語種別 | 英語 |
| 発行・発表の年月 | 2016/06 |
| 形態種別 | 研究論文 |
| 標題 | Self-organized charge puddles in a three-dimensional topological material |
| 執筆形態 | その他 |
| 掲載誌名 | PHYSICAL REVIEW B |
| 出版社・発行元 | AMER PHYSICAL SOC |
| 巻・号・頁 | 93(24) |
| 著者・共著者 | N. Borgwardt,J. Lux,I. Vergara,Zhiwei Wang,A. A. Taskin,Kouji Segawa,P. H. M. van Loosdrecht,Yoichi Ando,A. Rosch,M. Grueninger |
| 概要 | In three-dimensional (3D) topological materials, tuning of the bulk chemical potential is of crucial importance for observing their topological properties; for example, Weyl semimetals require chemical-potential tuning to the bulk Weyl nodes, while 3D topological insulators require tuning into the bulk band gap. Such tuning is often realized by compensation, i.e., by balancing the density of acceptors and donors. Here we show that in such a compensated 3D topological material, the possibility of local chemical-potential tuning is limited by the formation of self-organized charge puddles. The puddles arise from large fluctuations of the Coulomb potential of donors and acceptors. Their emergence is akin to the case of graphene, where charge puddles are already established as a key paradigm. However, there is an important difference: Puddles in graphene are simply dictated by the static distribution of defects in the substrate, whereas we find that puddles in 3D systems self-organize in a nontrivial way and show a strong temperature dependence. Such a self-organization is revealed by measurements of the optical conductivity of the bulk-insulating 3D topological insulator BiSbTeSe2, which pinpoints the presence of puddles at low temperatures as well as their surprising "evaporation" on a temperature scale of 30-40 K. The experimental observation is described semiquantitatively by Monte Carlo simulations. These show that the temperature scale is set by the Coulomb interaction between neighboring dopants and that puddles are destroyed by thermally activated carriers in a highly nonlinear screening process. This result indicates that understanding charge puddles is crucial for the control of the chemical potential in compensated 3D topological materials. |
| DOI | 10.1103/PhysRevB.93.245149 |
| ISSN | 2469-9950/2469-9969 |
| PermalinkURL | https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84976902210&origin=inward |