Magneto thermoelectric power of the doped polyacetylene

Thermoelectric power (TEP) and electrical conductivity of the metallic polp acetylene (PA) doped with AuCl3 and I-2 are measured under high magnetic fi eld up to 17 Tesla. We have observed the following two remarkable behaviors in the TEP results; (1) the temperature dependence of TEP for the iodine a nd metal-halide doped polyacetylene show clear difference at T<20K (2) abru pt reduction of the magneto TEP near 70K for both metal-halide and iodine d oped PAs. As the doping concentration increases, the reduction temperature of TEP increases from 70K to 120K. The reduction of magneto TEP could be du e to the SDW formation, since the collective motion can have lower entropy than that of the single particle transport.