Regensburg 2007 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 28: Transport - Poster Session
TT 28.8: Poster
Thursday, March 29, 2007, 14:00–17:45, Poster A
Hall effect and magnetoresistance of single-walled carbon nanotubes — •sung-ho jhang1,3, seung-hyun lee1, ursula dettlaff2, dongsu lee1, siegmar roth2, and yung-woo park1 — 1School of Physics, Seoul National University, Seoul, Korea — 2Max-Planck-Institute for solid state research, Stuttgart, Germany — 3Institute of Experimental and Applied Physics, University of Regensburg, Regensburg, Germany
We report Hall coefficient and magnetoresistance measurements on films and networks of single-walled carbon nanotubes(SWNTs). Four different types of SWNTs are prepared as films; Purified SWNTs synthesized either by HiPCO (High-Pressure CO Conversion) process or by laser ablation method (laser SWNTs), plus those SWNTs chemically treated by SOCl2. SOCl2-modified SWNTs show higher conductivity due to doping effect. The carrier density is determined to be ∼ 1022cm−3 for HiPCO or SOCl2-modified SWNTs, and ∼ 1021cm−3 for laser SWNTs. Considering that theoretically predicted carrier density of metallic SWNT is ∼ 1022cm−3 and that of semiconducting SWNT is ∼ 1020cm−3, the difference in carrier density between HiPCO and laser SWNTs can be originated from the difference in the ratio of metallic and semiconducting SWNTs in both films. While Hall coefficient is positive in the whole temperature range of 1.4-300K for HiPCO and SOCl2-modified SWNTs, Hall coefficient of laser SWNTs shows a sign change around T = 15K. The magnetoresistance of SWNTs studied in high magnetic fields up to 33T, and in a temperature range of 0.4-300K will be also presented.