Conductance Fluctuations in PbSe: Manifestation of Ballistic Transport in Macroscale?

Precise magnetoresistance measurements on microstructures of photolithographically patterned PbSe epilayers have been performed in the magnetic field range up to 17 Τ. Unusually large, reproducible magnetoconductance fluctuations have been observed. The fluctuation amplitude decreases exponentially with the magnetic field. A correlation magnetic field of the fluctuations corresponds to the Aharonov-Bohm effect which involves electron trajectories much smaller than the electron mean free path. This points strongly to the ballistic, not diffusive, origin of the observed phenomenon.