Dresden 2017 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 64: Poster 1

MA 64.16: Poster

Freitag, 24. März 2017, 09:30–13:00, P2-EG

Magnetoelectric properties in oxidized-graphenic nanoplatelets and thin films obtained from bamboo — •Katherine Gross¹, Jhon Jairo Prias-Barragán^{2, 3}, Luc Lajaunie⁴, Raul Arenal⁴, Hernando Ariza-Calderón², and Pedro Prieto¹ — ¹CENM, Universidad del Valle, Colombia — ²IIS, Universidad del Quindio, Colombia — ³EITP, Universidad del Quindio, Colombia — ⁴LMA, INA, Universidad de Zaragoza, Zaragoza, Spain

We employed a novel and cost-effective pyrolytic method to synthetize oxidized-graphenic nanoplatelets (OGNP) and thin films using bamboo, which is a cheap and highly renewable natural source. We have studied the magnetic response by systematically varying the crystal structure and topological defects. The crystal structure and the surface topography is modified by increasing the carbonization temperature in a range of 473K to 973K. At 973K OGNP present a higher ordered crystalline graphite structure and a sp2 fraction of 87 percent. OGNP show ferromagnetic order and low coercivity at room temperature. Magnetic properties are correlated with the presence of topological defects due to a natural formation of islands during the carbonization process. Magnetic force microscopy gives direct evidence for local ferromagnetic order at the topological defects. Temperature dependence on conductivity of the thin films showed typical semiconductor behavior, which could be described by the Mott 3D variable-range hopping mechanism. Hysteretic negative magnetoresistance (MR) was found in thin films, which confirms the intrinsic nature of the observed ferromagnetism. At 300 K the maximum MR is about 2 percent.