Samaddar Sayanti, Strasdas Jeff, Janßen Kevin, Just Sven, Johnsen Tjorven, Wang Zhenxing, Uzlu Burkay, Li Sha, Neumaier Daniel, Liebmann Marcus, Morgenstern Markus
2nd Institute of Physics B and JARA-FIT, RWTH Aachen University, Otto-Blumenthal-Straße, 52074 Aachen, Germany.
National Physical Laboratory, Hampton Road, Teddington TW11 0LW, United Kingdom.
Nano Lett. 2021 Nov 24;21(22):9365-9373. doi: 10.1021/acs.nanolett.1c01145. Epub 2021 Nov 4.
Dominating electron-electron scattering enables viscous electron flow exhibiting hydrodynamic current density patterns, such as Poiseuille profiles or vortices. The viscous regime has recently been observed in graphene by nonlocal transport experiments and mapping of the Poiseuille profile. Herein, we probe the current-induced surface potential maps of graphene field-effect transistors with moderate mobility using scanning probe microscopy at room temperature. We discover micrometer-sized large areas appearing close to charge neutrality that show current-induced electric fields opposing the externally applied field. By estimating the local scattering lengths from the gate dependence of local in-plane electric fields, we find that electron-electron scattering dominates in these areas as expected for viscous flow. Moreover, we suppress the inverted fields by artificially decreasing the electron-disorder scattering length via mild ion bombardment. These results imply that viscous electron flow is omnipresent in graphene devices, even at moderate mobility.
主导的电子-电子散射使得粘性电子流能够呈现出流体动力学电流密度模式，例如泊肃叶分布或涡旋。最近通过非局部输运实验和泊肃叶分布测绘在石墨烯中观测到了粘性 regime。在此，我们在室温下使用扫描探针显微镜探测具有中等迁移率的石墨烯场效应晶体管的电流诱导表面电势图。我们发现靠近电荷中性出现的微米级大面积区域呈现出与外部施加场相反的电流诱导电场。通过从局部面内电场的栅极依赖性估计局部散射长度，我们发现电子-电子散射在这些区域占主导，正如粘性流所预期的那样。此外，我们通过温和的离子轰击人为降低电子-无序散射长度来抑制反向场。这些结果意味着粘性电子流在石墨烯器件中无处不在，即使在中等迁移率下也是如此。
