Regensburg 2016 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 91: Poster IIIb (Joint session of DS and HL, organized by HL)
HL 91.12: Poster
Donnerstag, 10. März 2016, 16:00–19:00, Poster A
Magneto Transport Properties of Mesoscopic HOPG Graphite Flakes: Thickness Dependence — •Mahsa Zoraghi1, José Barzola-Quiquia1, Markus Stiller1, Tobias Lühmann2, and Pablo Esquinazi1 — 1Division for Superconductivity and Magnetism, Faculty of Physics and Earth Sciences, University of Leipzig, Linnestr. 5, D-04103, Germany — 2Institute for Medicine Physics and Biophysics, University of Leipzig, 04107 Leipzig
The electrical transport properties of mesoscopic thin graphite flakes (HOPG) as function of temperature and magnetic field were investigated. Samples were measured in the range of 2 up to 310 K and magnetic fields of ±7 T. The temperature dependendent resistance R(T) shows that samples thicker than ≈35 nm have metallic behavior and thinner samples show semiconducting-like behavior. The resistivity increases with decreasing sample thickness. We explained the R(T) measurements using a model, which considers contributions in parallel. A contribution behaving like a 2DEG system formed at the interfaces of the crystals inside the sample; the other has a semiconducting behavior, which we attribute to the crystalline regions. The MR measurements show a thickness dependence, i.e. the change is reduced by reducing the thickness of the sample. Shubnikov de Haas (SdH) oscillations are more pronounced in thick samples, and show that the conductivity in our samples is dominated by two types of carriers. The results indicate that transport properties of bulk graphite are not intrinsic and depend on the interfaces. Raman results reveal that all of the samples have the same structural quality as of bulk HOPG.