Interplay between magnetism and conductivity in the one-dimensional organic conductor TPP [Fe (Pc) (CN) 2] 2

The strongly nonlinear current-voltage (I-V) characteristics and the large negative magnetoresistance (MR) are observed at low temperatures in the one-dimensional organic conductor TPP [Fe (Pc) (CN) 2] 2. The nonlinear I-V curves are interpreted as the transport of the electrons and holes excited from the charge ordered state on the Fe (Pc) (CN) 2 chains, whose energy gap strongly depends on electric fields. The negative MR is enhanced as temperature decreases, and the resistance steeply changes over four orders of magnitude around 15 T at 1.5 K. This decrease is associated with a magnetic torque anomaly, and the energy gap is rapidly reduced around 15 T. The detailed analyses of the I-V curves show that the electric flux distribution, i.e., the dimensionality of the Coulomb interaction between the carriers, also changes around 15 T.