Universal activation barriers for metastable metal nanowires

We introduce a continuum approach to study the lifetimes of monovalent metal nanowires, which includes the competing effects of surface tension and electron-shell structure on an equal footing. Thermal fluctuations of cylindrical nanowires are modeled through the use of stochastic Ginzburg-Landau field theories. The fluctuation-induced thinning of metal nanowires is predicted to occur via the nucleation of surface kinks at the ends of the wire, consistent with recent electron microscopy studies. The activation barriers of the most stable structures are predicted to be ``universal,'' i.e., independent of the radius of the wire, and proportional to the square root of the surface tension. The reduction of the activation barrier under strain is also determined.