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 (Formula presented) given by the transverse field strength at which one quantum of flux (Formula presented) passes through a rectangle with sides set by the layer-spacing a and the elastic mean free path (Formula presented) Experimental measurement of this magnetoresistance may, therefore, provide a direct determination of the elastic mean free path in the chiral metal.