Imaging the Breakdown of Ohmic Transport in Graphene
Imaging the Breakdown of Ohmic Transport in Graphene
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DOI：
10.1103/physrevlett.129.087701
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发表时间：
2022-08-17
影响因子：
8.6
通讯作者：
Jayich, Ania C. Bleszynski
中科院分区：
文献类型：
--
作者：
Jenkins, Alec;Baumann, Susanne;Jayich, Ania C. Bleszynski
欧姆定律描述了电流密度和电场的比例关系。在固态导体中，欧姆定律是由于电子散射过程使电流松弛而出现的。在这里，我们使用氮空位中心磁力直接成像欧姆定律在一个狭窄的收缩制造在一个高迁移率的石墨烯单层的局部故障。欧姆流动在室温下是可见的，因为电流集中在收缩边缘，流动曲线完全由样品的几何形状决定。然而，当温度降低到200 K以下时，电流集中在收缩中心附近。在流动模式的变化是一致的交叉从扩散到粘性电子传输为主的电子-电子散射过程，不放松电流。
Ohm's law describes the proportionality of the current density and electric field. In solid-state conductors, Ohm's law emerges due to electron scattering processes that relax the electrical current. Here, we use nitrogen-vacancy center magnetometry to directly image the local breakdown of Ohm's law in a narrow constriction fabricated in a high mobility graphene monolayer. Ohmic flow is visible at room temperature as current concentration on the constriction edges, with flow profiles entirely determined by sample geometry. However, as the temperature is lowered below 200 K, the current concentrates near the constriction center. The change in the flow pattern is consistent with a crossover from diffusive to viscous electron transport dominated by electron-electron scattering processes that do not relax current.