Transverse magnetoresistance of the two-dimensional chiral metal

We consider the two-dimensional chiral metal, which exists at the surface of a layered, three-dimensional sample exhibiting the integer quantum Hall effect. We calculate its magnetoresistance in response to a component of magnetic field perpendicular to the sample surface, in the low temperature, but macroscopic, regime where inelastic scattering may be neglected. The magnetoresistance is positive, following a Drude form with a field scale B-0 = Phi(0)/al(el) given by the transverse field strength at which one quantum of flux Phi(0) passes through a rectangle with sides set by the layer-spacing a and the elastic mean free path l(el). Experimental measurement of this magnetoresistance may, therefore, provide a direct determination of the elastic mean free path in the chiral metal. [S0163-1829(99)05807-5].