A STM technique to study bulk properties

MAR 04, 2009

Physics Today

Science :Every once in a while, experiments are reported that apply existing tools to apparently well-understood scientific concepts and come up with tantalizing, novel results. In Science magazine , such a case is beautifully demonstrated by Weismann and colleagues. They use scanning tunneling microscopy (STM), a standard surface science technique, to visualize electron flow in the bulk of a piece of copper.

Primarily based on its atomic resolution imaging capability, the STM has had phenomenal success in the field of surface science. How can a truly surface-sensitive technique be used to measure a bulk property? The key trick applied by Weismann et al. is to exploit the wave nature of the electrons in copper and study their interference patterns on the surface caused by scattering centers in the bulk of the material. Their technique opens the door to a real-space investigation of electron propagation in materials and to the scattering of electrons at defects well below the surface.