Effect of a mixed scattering potential on the conductance fluctuations of a quasi-ballistic wire

We investigate experimentally the conductance fluctuations in a high-mobility quantum wire. These fluctuations are found to differ from the universal-type expected for a diffusive system. With applied magnetic field the amplitude and quasi-period of the fluctuations are both enhanced at the field at which maximum boundary-roughness scattering occurs. We explain our results in terms of ballistic trajectories, prevalent in the centre of the wire, being deflected by the field into the impurities in the boundaries which scatter them diffusively.