Condensed-matter physics: Glasses made from pure metals

The experimental realization of amorphous pure metals sets the stage for studies of the fundamental processes of glass formation, and suggests that amorphous structures are the most ubiquitous forms of condensed matter. See Letter P.177 If the cooling rate is sufficiently fast, it is thought that any metallic liquid can be frozen into a glassy state, which can in turn yield a solid metal with unusual and potentially useful mechanical properties. In practice, such glass formation is mainly limited to metals composed of two or more elements: the cooling rates required to produce a monatomic metallic glass are usually too high to be achieved experimentally. Li Zhong et al. have found a way around this experimental difficulty. They have developed a nanoscale heating system in which a pulsed electrical current can locally melt the metal (briefly forming a small volume of metallic liquid), which then rapidly loses its heat into the surrounding solid bulk and leaves behind a sample of monatomic metallic glass amenable for study of its structure and properties.