Effect of short-range impurities on low-temperature conductance and   thermopower of quantum wires
  The electron transport through the parabolic quantum wire placed in longitudinal magnetic field in the presence of the system of short-range impurities inside the wire is investigated. Using approach based on the zero-range potential theory we obtained an exact formula for the transmission coefficient of the electron through the wire that allows to calculate such the transport characteristics as the conductance and differential thermopower. The dependencies of conductance and thermopower on the chemical potential and magnetic field are investigated. The effect of elastic scattering due to short-range impurities on low-temperature conductance and thermopower is studied. It was shown that the character of the electron transport essentially depends on the position of the every scattering center. The presence even isolated impurity leads to destruction of conductance quantization. In some cases it is possible that thermopower can change the sign in dependence on chemical potential and magnetic field. 
I.A. Kokurin, V.A. Margulis