Magnetotransport and the Shubnikov-de Haas effect in quasi-two-dimensional purple bronze TlMo6O17

Magnetotransport properties of quasi-two-dimensional thallium purple bronze were measured at different magnetic fields for H ∥ c . Huge positive magnetoresistance below the Peierls transition T P and Shubnikov-de Haas oscillation in the high-field range were found. In the charge-density-wave (CDW) state below T P , nonlinearity of the voltage-current characteristics due to the depinning of a CDW was also observed at 2 K and 14 T. These results supported the suggestion that the CDW gap opening below T P still leaves small electron and/or hole pockets, but an applied magnetic field can remove these pockets to a great extent, thus leading to an enhanced gap.