Ballistic Electron Transport Characteristics in High-Purity Aluminum Single Crystals

Abstract

Negative bend resistance was observed at 4.2 K in cross‐shaped specimens cut from a high‐purity aluminum single crystal with a residual resistance ratio RRR of about 100000. The cross section of arms of the specimens was 0.5×0.4 mm2 and the bulk mean free path lb of conduction electrons in the material was about 3 mm. The negative bend resistance was enhanced in a magnetic field parallel to a pair of arms. Nonlinear I–V characteristics were observed when one of the potential probes was placed on an arm at a distance less than lb from the center of the intersection of the arms. Besides, the I–V characteristics depended strongly on the volume of a reservoir for incident electrons, left behind the potential probe. The negative bend resistance and the nonlinear I–V characteristics were attributed to the ballistic conduction of electrons. The orientation dependence of the ballistic conduction was also examined.