Biphase Ordering of Iron Oxide Surfaces

Abstract

Scanning tunneling microscopy and low energy electron diffraction have been used to study the $\ensuremath{\alpha}{\ensuremath{-}\mathrm{F}\mathrm{e}}_{2}{\mathrm{O}}_{3}(0001)$ surface in an ultrahigh vacuum. Our results show that this surface can be stabilized by coexisting $\ensuremath{\alpha}{\ensuremath{-}\mathrm{F}\mathrm{e}}_{2}{\mathrm{O}}_{3}(0001)$ and FeO(111) phases, with each phase existing in atomically well-ordered islands of mesoscopic dimensions. Furthermore, the islands themselves are arranged to form a superlattice. The formation of this superlattice can be explained in terms of the lattice mismatch between two types of oxygen sublattices.