Kim Hyo Won, Jung Junseo, Lee Gahee, Park Taesu, Jang Won-Jun, Kim Hoil, Kim Jun Sung, Shim Ji Hoon, Yang Bohm-Jung, Jeon Sangjun
Samsung Advanced Institute of Technology, Suwon, 13595, Republic of Korea.
Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Republic of Korea.
Adv Sci (Weinh). 2025 Feb;12(8):e2407437. doi: 10.1002/advs.202407437. Epub 2025 Jan 7.
The fundamental characteristics of collective interactions in topological band structures can be revealed by the exploration of charge screening in topological materials. In particular, distinct anisotropic screening behaviors are predicted to occur in Dirac nodal line semimetals (DNLSMs) due to their peculiar anisotropic low-energy dispersion. Despite the recent extensive theoretical research, experimental observations of exotic charge screening in DNLSMs remain elusive, which is partly attributed to the coexisting trivial bands near the Fermi energy. This study reports the first direct observation of highly anisotropic charge-screening behavior in the DNLSM SrAs. Through atomically resolved conductance measurements, a highly anisotropic charge-screening pattern around charged impurities on a surface is demonstrated. Moreover, the combination of model studies and first-principles calculations reveals the unique nature of the screening anisotropy in DNLSMs. The results of this study are expected to pave the way for understanding the profound collective behavior of interacting low-energy fermions in topological materials.
拓扑能带结构中集体相互作用的基本特征可以通过研究拓扑材料中的电荷屏蔽来揭示。特别是，由于狄拉克节线半金属（DNLSMs）具有特殊的各向异性低能色散，预计会出现独特的各向异性屏蔽行为。尽管最近有广泛的理论研究，但DNLSMs中奇异电荷屏蔽的实验观测仍然难以实现，这部分归因于费米能级附近共存的平凡能带。本研究报告了在DNLSM SrAs中首次直接观测到高度各向异性的电荷屏蔽行为。通过原子分辨电导测量，展示了表面带电杂质周围高度各向异性的电荷屏蔽图案。此外，模型研究和第一性原理计算的结合揭示了DNLSMs中屏蔽各向异性的独特性质。本研究结果有望为理解拓扑材料中相互作用的低能费米子的深刻集体行为铺平道路。
