STM-induced flip-flop switching of adsorbed subphthalocyanine molecular arrays

A reversible, orientational switching of subphthalocyanine molecules was observed with a scanning tunneling microscope. The asymmetric, polar molecules adsorbed in an epitaxial array on a copper (100) surface, initially with its axial chlorine atom either upward or downward. After scanning at a negative bias the upward molecules turn upside down, while all molecules switched to the upward orientation at a positive bias. This flip-flop switching of the molecular array would lead to an information density of similar to60 Tbit/cm(2).