Berlin 2015 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 34: Transport: Graphene (jointly with CPP, DS, DY, HL, MA, O)
TT 34.2: Vortrag
Dienstag, 17. März 2015, 09:45–10:00, A 053
Magnetoresistance of nanocrystalline and ion-irradiated graphene — •Paul Linsmaier1, Lorenz Weiss1, Armin Shaukat1, Christian Bäuml1, Daniel Steininger1, Ina Schneider1, Matthias Büenfeld2, Nils-Eike Weber2, Andrey Turchanin2, Miriam Grothe3, Thomas Weimann3, Ferdinand Kißlinger4, Heiko B. Weber4, and Christoph Strunk1 — 1Inst. f. Exp. and Appl. Physics, University of Regensburg — 2Fac. of Physics, University of Bielefeld — 3Physikalisch-Technische Bundesanstalt, Braunschweig — 4Fac. of Physics, F.-A. University Erlangen-Nürnberg
We investigate the magnetotransport in Hall bar structures of nanocrystalline graphene [1] compared to Ar+-bombarded epitaxial graphene [2]. We measured the resistance R(T) and R(B) for samples with different sheet resistance (10-40 kΩ/sq at T=300 K). The I-V characteristics of both types show strong non-linear behavior at low temperatures. Low resistive samples of nanocrystalline graphene show positive magnetoresistance (MR) with values up to + 60 % in perpendicular magnetic field for temperatures below a crossover temperature. Above this temperature the MR becomes negative. The perpendicular MR in the ion-bombarded graphene was always negative. In parallel magnetic field the MR exhibits large positive values up to + 700 % in the nanocrystalline graphene. Strongly non-monotonic behavior of the MR was observed in the ion-bombarded sample in parallel field.
[1] A. Turchanin et al., ACS Nano 5 (2011).
[2] K. V. Emtsev et al., Nat. Mat. 8, 203 - 207 (2009).