LANDAUER RESISTIVITY DIPOLE IN A STRONG MAGNETIC-FIELD

We consider a localized single impurity in a two-dimensional electron gas with a perpendicular magnetic field at filling factor 1. A scatter ing theory calculation is performed for the local electron density aro und the impurity in the presence of a finite transport current. It is shown that the current-induced Landauer resistivity dipole is rotated by 90 degrees compared with the situation in the absence of a magnetic field. This behavior naturally reflects the structure of the resistiv ity tensor, with a finite value of rho(xy) but vanishing longitudinal resistivity rho(l) due to the absence of backscattering. We briefly di scuss the implications of our results on the potential distribution in the quantum Hall effect, and for scanning tunneling microscopy measur ements of the local density of states.