RESISTIVITY AND HALL RESISTANCE OF A 2-DIMENSIONAL ELECTRON-GAS IN THE PRESENCE OF MAGNETIC-FLUX TUBES

We compute the Hall and diagonal resistivities of a two-dimensional el ectron gas in the presence of randomly placed magnetic flux tubes. It is found that there is a suppression of the Hall conductance below its expected value for the corresponding uniform magnetic field case at l ow electron densities, in agreement with recent experiments. At densit ies somewhat lower than achieved thus far experimentally, we find reso nances in the transport coefficients due to Landau level structures in the flux tubes. A classical calculation of the Hall resistance reprod uces the broad features of the Hall conductance for integral or half-i ntegral numbers of flux quanta in each flux tube.