I-V characteristics and differential conductance fluctuations of Au nanowires

Electronic transport properties of Au nano-structure are investigated using both experimental and theoretical analysis. Experimentally, stable Au nanowires were created using mechanically controllable break junction in air, and simultaneous current-voltage (I-V) and differential conductance $\delta I/\delta V$ data were measured. The atomic device scale structures are mechanically very stable up to bias voltage $V_b\sim0.6V$ and have a life time of a few $minutes$. Facilitated by a shape function data analysis technique which finger-prints electronic properties of the atomic device, our data show clearly differential conductance fluctuations with an amplitude $>1%$ at room temperature, and a nonlinear I-V characteristics. To understand the transport features of these atomic scale conductors, we carried out {\it ab initio} calculations on various Au atomic wires. The theoretical results demonstrate that transport properties of these systems crucially depend on the electronic properties of the scattering region, the leads, and most importantly the interaction of the scattering region with the leads. For ideal, clean Au contacts, the theoretical results indicate a linear I-V behavior for bias voltage $V_b