Superconducting ultra narrow Al nanowires

We have successfully developed a technique\footnote{F. Altomare \textit{et al.},\textit{March Meeting 2001}}$^,$\footnote{F. Altomare \textit{et al.},\textit{March Meeting 2004}} for the fabrication of nanowires, of width comparable or smaller to 10~nm, using the (1$\bar{1}0 $) plane of a narrow MBE-grown ridge as a template. These wires are formed with direct connections to 4 terminal measurement pads. The versatility and reliability (yield exceeding 75\%) in the fabrication process, together with the small lateral size achievable, makes this technique uniquely suited for the study of diverse physical phenomena in nanowires composed of a variety of materials. In particular we have characterized AuPd wires as long as 20~$\mu$m and Al wires with length exceeding 10~$\mu$m. The Al wires superconduct at low temperature despite having a normal state resistance much greater than the superconducting quantum resistance($=\hbar/4e^2$). We will discuss the observed behavior of the normal-superconducting transition in applied magnetic field and the Current-Voltage characteristics of these wires. This work has been supported by NSF DMR 0135931 and 0401648.