FRACTIONAL QUANTUM CONDUCTANCE IN GOLD NANOWIRES

The conductance of a nanoscopic wire decreases in steps when it is str etched until it breaks. This is due to narrowing of the wire whereby q uantized conductance channels sequentially close. However the conducta nce plateaus seldom occur at integral multiples of the quantum of cond uctance G(0) and most steps are much smaller than G(0). High speed pre cision measurements of the conductance steps reveal that the nanowires are composed of not one but several quantized conductors in series an d that a step is caused by a quantized conductance change in one of th e elements in the sequence. Resolved series conductance quanta up to 2 0 G(0) have been observed at room temperature. The effect is explained in terms of elastic electronic scattering and has important consequen ces for nano-electronic circuitry.