Topological character of excitations in strongly correlated electronic systems: confinement and dimensional crossover

Topologically nontrivial states, the solitons, emerge as elementary excitations in 1D electronic systems. In a quasi 1D material the topological requirements originate the spin- or charge-roton like configurations with charge- or spin-kinks localized in the core. The rotons possess semi-integer winding numbers which results in the spin-charge recombination due to confinement and the combined symmetry. Practically important is the case of the spinon functioning as the single electronic pi-junction in a quasi 1D superconducting material. (C) 2002 Elsevier Science B.V. All rights reserved.