L. Casparis, D. Hug, D. Kölbl, D. M. Zumbühl
We present electrical transport measurements in natural graphite and highly ordered pyrolytic graphite (HOPG), comparing macroscopic samples with exfoliated, nanofabricated specimen of nanometer thickness. Nano-samples exhibit a very large c-axis resistivity \rho_c - much larger than expected from simple band theory - and non-monotonic temperature dependence, similar to macroscopic HOPG, but in stark contrast to macroscopic natural graphite. A recent model of disorder induced delocalization is consistent with the data. Micro-Raman spectroscopy reveals clearly reduced disorder in exfoliated samples and HOPG, as expected within the model - therefore presenting further evidence for a novel paradigm of electronic transport in graphite.
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http://arxiv.org/abs/1301.2727
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