Boundary-mediated electron-electron interactions in quantum point   contacts
  An unusual increase of the conductance with temperature is observed in clean quantum point contacts for conductances larger than 2e^2/h. At the same time a positive magnetoresistance arises at high temperatures. A model accounting for electron-electron interactions mediated by bound- aries (scattering on Friedel oscillations) qualitatively describes the observation. It is supported by numerical simulation at zero magnetic field. 
Vincent Thomas Francois Renard (NTT, BRL, LCMI), O. A. Tkachenko   (LCMI, Institute of semiconductor Physics), V.A. Tkachenk...