Two-Impurity Scattering in Quasi-One-Dimensional Systems

In a quasi-one-dimensional system (a tube) with low concentration of defects n , the resistivity ρ has peaks (van-Hove singularities) as a function of the Fermi energy. We show that due to non-Born scattering effects a deep narrow gap should appear just in the center of each peak. The resistivity at the bottom of a gap ( ) is dominated by scattering at rare “twin” pairs of close defects, while scattering at solitary defects is suppressed. The predicted effect is characteristic for multichannel systems, it cannot be observed in strictly one-dimensional one.