Imaging coherent transport in graphene (part II): probing weak localization
Imaging coherent transport in graphene (part II): probing weak localization
复制标题
石墨烯中的相干传输成像（第二部分）：探测弱定位
作者：
J. Berezovsky;R. Westervelt
石墨烯开辟了量子输运研究的新途径，具有潜在的相干电子学应用前景。相干传输敏感地依赖于石墨烯样品中存在的微观无序的散射：沿不同路径传播的电子波相互干扰，改变了总电导。弱局域化是由波的相干后向散射产生的，而普遍的电导波动是通过对所有路径求和而产生的。在这项工作中，我们使用液氦冷却的扫描探针显微镜，通过在石墨烯装置中创建可移动的散射体，获得了微弱局域化的电导图像。这项技术使我们能够用大小与电子波长相当的探测器来研究相干输运。磁导与尖端位置关系的图像通过移动单个散射体来映射无序的影响，揭示了电子干扰是如何被尖端微扰所修正的。通过平均尖端产生的散射体不同位置处的磁导轨迹，得到了B=0时电导率的微弱局域化凹陷。DIP的宽度ΔBWL给出了固定电荷密度下电子相干长度Lϕ的估计值。这种“扫描散射体”方法通过直接扰乱产生这些干涉效应的无序构型，为研究石墨烯中的相干输运提供了一种新的方法。
Graphene has opened new avenues of research in quantum transport, with potential applications for coherent electronics. Coherent transport depends sensitively on scattering from microscopic disorder present in graphene samples: electron waves traveling along different paths interfere, changing the total conductance. Weak localization is produced by the coherent backscattering of waves, while universal conductance fluctuations are created by summing over all paths. In this work, we obtain conductance images of weak localization with a liquid-He-cooled scanning probe microscope, by using the tip to create a movable scatterer in a graphene device. This technique allows us to investigate coherent transport with a probe of size comparable to the electron wavelength. Images of magnetoconductance versus tip position map the effects of disorder by moving a single scatterer, revealing how electron interference is modified by the tip perturbation. The weak localization dip in conductivity at B = 0 is obtained by averaging magnetoconductance traces at different positions of the tip-created scatterer. The width ΔBWL of the dip yields an estimate of the electron coherence length Lϕ at fixed charge density. This ‘scanning scatterer’ method provides a new way of investigating coherent transport in graphene by directly perturbing the disorder configuration that creates these interferometric effects.
影响因子：
8.6
作者：
Tikhonenko, F. V.;Horsell, D. W.;Savchenko, A. K.
通讯作者：
Savchenko, A. K.
影响因子：
2.1
作者：
Horsell, D. W.;Savchenko, A. K.;Fal'ko, V. I.
通讯作者：
Fal'ko, V. I.