Imaging the breaking of electrostatic dams in graphene for ballistic and viscous fluids

• 成果类型: Article
• 署名作者: Krebs, Zachary J.; Behn, Wyatt A.; Li, Songci; Smith, Keenan J.; Watanabe, Kenji; Taniguchi, Takashi; Levchenko, Alex; Brar, Victor W.
• 署名单位: University of Wisconsin System; University of Wisconsin Madison; National Institute for Materials Science; National Institute for Materials Science
• 刊物名称: SCIENCE
• ISSN/ISSBN: 0036-9079
• DOI: 10.1126/science.abm6073
• 发表日期: 2023-02-17
• 页码: 671-676
• 关键词: scanning-tunneling-microscope; residual-resistivity dipole; resistance; transport; FLOW; conduction; electrons; vortices

摘要

The charge carriers in a material can, under special circumstances, behave as a viscous fluid. In this work, we investigated such behavior by using scanning tunneling potentiometry to probe the nanometer-scale flow of electron fluids in graphene as they pass through channels defined by smooth and tunable in-plane p-n junction barriers. We observed that as the sample temperature and channel widths are increased, the electron fluid flow undergoes a Knudsen-to-Gurzhi transition from the ballistic to the viscous regime characterized by a channel conductance that exceeds the ballistic limit, as well as suppressed charge accumulation against the barriers. Our results are well modeled by finite element simulations of two-dimensional viscous current flow, and they illustrate how Fermi liquid flow evolves with carrier density, channel width, and temperature.