Magneto thermoelectric power of the doped polyacetylene

Thermoelectric power (TEP) and electrical conductivity of the metallic polpacetylene (PA) doped with AuCl3 and I-2 are measured under high magnetic field 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 and metal-halide doped polyacetylene show clear difference at T<20K (2) abrupt reduction of the magneto TEP near 70K for both metal-halide and iodine doped PAs. As the doping concentration increases, the reduction temperature of TEP increases from 70K to 120K. The reduction of magneto TEP could be due to the SDW formation, since the collective motion can have lower entropy than that of the single particle transport.