Weigang Wang, Ko Munakata, Michael Rozler, Malcolm R. Beasley
Under mesoscopic conditions, the transport potential along a current carrying sample is expected to exhibit spatial variations due to quantum mechanics. Scanning tunneling potentiometry is the ideal tool to investigate such variations, by virtue of its high spatial resolution. We report in this {\it Letter} the first detailed measurement of the transport potential under mesoscopic conditions using epitaxial graphene as our demonstration sample. Tip jumping artifacts are a major possible contribution to systematic errors; and we mitigate such problems by using custom-made slender and sharp tips manufactured by focussed ion beam. In addition to residual resistive dipoles associated with topographical defects, features in transport potential in more homogenous regions were observed in the local potential maps. These features include oscillations and localized peaks and dips in the potential.
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http://arxiv.org/abs/1211.6088
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