Colloquium

Department of Physics & Astronomy

The vanishing magneto resistance of polyacetylene nanofibers: Supermagnetoconductivity

September 8, 2010l Hit 923
Date : September 8, 2010 16:00 ~
Speaker : Yung Woo Park(SNU)
Professor :
Location : 56동106호
Results of nonlinear magneto resistance (MR) of polyacetylene nanofibers in high magnetic field up to H = 30 tesla at low temperature T = 1.5 K are presented. The MR was proven to be of the spin origin; it reaches 16 % at highest H. Unexpectedly, the MR was suppressed by increasing electric field E, vanishing at E ≥ 2 10 V/cm. It is understood that the doping induced spinless charged soliton pairs, which are initially confined to a certain distance because of the interchain phase correlations, are deconfined in high electric fields, resulting in a vanishing magneto resistance (VMR). The role of the specific, degenerate ground state of the polyacetylene is confirmed by parallel studies of the different magneto resistance of polyaniline nanofibers which contrarily is not affected by the electric field. The VMR in high electric field of polyacetylene nanofibers is named as the supermagnetoconductivity in analogy to the zero resistance of superconductivity.
A. Choi et al., Synthetic Metals 160, 1349-1353 (2010)
Y. W. Park, Chemical Society Reviews 39, 2428-2438 (2010)