Conductance structures in one-dimensional quantum contact

Full text: Very short quantum wires (quantum contacts) exhibit a conductance structure at the value of conductance close to 0.7 x 2e2/h. The structure was discovered by Thomas et al and dependence of the structure on the longitudinal magnetic field was studied in the same experiment. This dependence has clearly demonstrated that the effect is related to the electron spin. In longer contacts the structure evolves to the lower values of conductance. In the present work we develop theory of the structure. We demonstrate that this structure is related to the charge density waves within the contact. This is a precursor for Wigner crystallization. The exchange electron-electron interaction is crucial for development of the charge density waves, so in agreement with experiment the effect is intrinsically related to spin. Many-body Hartree-Fock calculations of conductance are performed with and without the longitudinal magnetic field. Results of the calculations are in good agreement with experimental data