Persistent current in a disordered mesoscopic ring with many channels: Scattering-matrix based calculation

We calculate numerically the persistent electron current in a disordered quasi-one-dimensional conducting ring with many channels, made of the two-dimensional conductor of finite width W and length L⪢W. The elastic mean free path l is limited by two different types of disorder. (i) The impurity disorder is modelled (in two dimensions) by the δ-function-like-potential barriers with random positions and signs. (ii) Disorder due to the sample-edge roughness is modelled as rectangular steps added or subtracted at random at both sample edges. Transport across disorder is described by the scattering-matrix method. Especially in the sample with disordered sample edges, the calculated typical persistent current exceeds remarkably the theoretical result Ityp=1.56(evF/L)(l/L), known to strongly underestimate experimental data.