Evidence for Local Spots of Viscous Electron Flow in Graphene at Moderate Mobility.
Evidence for Local Spots of Viscous Electron Flow in Graphene at Moderate Mobility.
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DOI：
10.1021/acs.nanolett.1c01145
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发表时间：
2021-03
期刊：
影响因子：
10.8
通讯作者：
S. Samaddar;J. Strasdas;Kevin Janßen;Sven Just;T. Johnsen;Zhenxing Wang;B. Uzlu;Sha Li;D. Neumaier;M. Liebmann;M. Morgenstern
中科院分区：
文献类型：
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作者：
S. Samaddar;J. Strasdas;Kevin Janßen;Sven Just;T. Johnsen;Zhenxing Wang;B. Uzlu;Sha Li;D. Neumaier;M. Liebmann;M. Morgenstern
占主导地位的电子-电子散射使得粘性电子流能够表现出流体动力学电流密度模式，例如Poiffille分布或涡旋。粘性制度最近已被观察到在石墨烯中的非本地传输实验和映射的Poietille配置文件。在这里，我们探测的电流诱导的表面电位图的石墨烯场效应晶体管具有中等的流动性，在室温下使用扫描探针显微镜。我们发现微米大小的大面积出现接近电荷中性，显示电流感应电场反对外部施加的领域。通过估计局部散射长度从门依赖的局部面内电场，我们发现，电子-电子散射占主导地位，在这些领域的预期粘性流。此外，我们通过温和的离子轰击来人为地减小电子无序散射长度来抑制反转场。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。
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.