Resonantly-enhanced transmission through a periodic array of subwavelength apertures in heavily-doped conducting polymer films Appl. Phys. Lett. 88, 071101 (2006); 10.1063/1.2175482 Magnetotransport properties of alkali metal doped La-Ca-Mn-O system under pulsed magnetic field: Decrease of small polaron coupling constant and melting of polarons in the high temperature phaseThe magnetoconductivity of two kinds of iodine doped helical polyacetylene, R-and S-polyacetylene, were investigated to understand the effect of the intrafibril and the interfibrillar interaction in the polyacetylene system. The zero-field resistivity ratio, r ϭ(1.2 K͒/͑300 K͒, is comparable to that of stretch-oriented high-density polyacetylene film, which indicates the partial alignment of chains inside a polymer fiber. At low magnetic fields, the small negative component of magnetoconductivity ͑positive magnetoresistance͒ was observed and its magnitude increases as the r value increases. In the high field region, the magnetoconductivity is positive and it clearly shows the linear dependence on the magnetic field up to Hϭ30 T. The linear field dependence of magnetoconductivity is different from what is expected in the three-dimensional localization-interaction picture. For the same r value samples, the magnitude of negative magnetoconductivity of S-polyacetylene is much bigger than that of R-polyacetylene, which could be attributed to the difference in the degree of helicity determining the strength of interfibrillar interaction.