Impurity pinning in transport through 1D Mott-Hubbard and spin gap insulators

A low energy crossover [V.V. Ponomarenko, N. Nagaosa, Phys. Rev. Lett. 81 ( 1998) 2304] induced by Fermi liquid reservoirs in transport through a 1D Mo tt-Hubbard insulator of finite length L is examined in the presence of impu rity pinning. Under the assumption that the Hubbard gap 2M is large enough: M > T-L drop nu(c)/L (nu(c): charge velocity in the wire) and the impurity backscattering rate Gamma(1) much less than T-L, the conductance vs, volta ge/temperature displays a zero-energy resonance. Transport through a spin g apped ID system is also described availing of duality between the backscatt ered current of this system and the direct. current of the Mott-Hubbard ins ulator. (C) 2000 Elsevier Science Ltd. All rights reserved.