Magnetoresistance of a two-dimensional electron gas in a parallel   magnetic field
  The conductivity of a two-dimensional electron gas in a parallel magnetic field is calculated. We take into account the magnetic field induced spin-splitting, which changes the density of states, the Fermi momentum and the screening behavior of the electron gas. For impurity scattering we predict a positive magnetoresistance for low electron density and a negative magnetoresistance for high electron density. The theory is in qualitative agreement with recent experimental results found for Si inversion layers and Si quantum wells. 
V.T.Dolgopolov (Institute of Solid State Physics, Chernogolovka,   Russia) A.Gold (Centre d'Elaboration de Mat\'eriaux et d'...