Zhang Yu, Gao Fei, Gao Shiwu, Brandbyge Mads, He Lin
School of Integrated Circuits and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing 100081, China.
Advanced Research Institute of Multidisciplinary Sciences, Beijing Institute of Technology, Beijing 100081, China.
Phys Rev Lett. 2022 Aug 26;129(9):096402. doi: 10.1103/PhysRevLett.129.096402.
Intervalley scattering involves microscopic processes that electrons are scattered by atomic-scale defects on the nanoscale. Although central to our understanding of electronic properties of materials, direct characterization and manipulation of range and strength of the intervalley scattering induced by an individual atomic defect have so far been elusive. Using scanning tunneling microscope, we visualize and control intervalley scattering from an individual monovacancy in graphene. By directly imaging the affected range of monovacancy-induced intervalley scattering, we demonstrate that it is inversely proportional to the energy; i.e., it is proportional to the wavelength of massless Dirac fermions. A giant electron-hole asymmetry of the intervalley scattering is observed because the monovacancy is charged. By further charging the monovacancy, the bended electronic potential around the monovacancy softens the scattering potential, which, consequently, suppresses the intervalley scattering of the monovacancy.
谷间散射涉及电子被纳米尺度的原子尺度缺陷散射的微观过程。尽管这对于我们理解材料的电子性质至关重要，但迄今为止，由单个原子缺陷引起的谷间散射的范围和强度的直接表征和操控仍然难以实现。利用扫描隧道显微镜，我们可视化并控制了石墨烯中单个单空位的谷间散射。通过直接成像单空位诱导的谷间散射的影响范围，我们证明其与能量成反比；即，它与无质量狄拉克费米子的波长成正比。由于单空位带电，观察到谷间散射存在巨大的电子 - 空穴不对称性。通过进一步给单空位充电，单空位周围弯曲的电子势使散射势软化，从而抑制了单空位的谷间散射。
