AVS 53rd International Symposium
    Surface Science Thursday Sessions
       Session SS-ThP

Paper SS-ThP13
Study of Step Stability on the Fe@sub 3@O@sub 4@ (100) Surface*

Thursday, November 16, 2006, 5:30 pm, Room 3rd Floor Lobby

Session: Surface Science Poster Session
Presenter: H.-Q. Wang, Yale University
Authors: H.-Q. Wang, Yale University
E.I. Altman, Yale University
V.E. Henrich, Yale University
Correspondent: Click to Email
The atomic structure along steps on metal oxide surfaces is crucial to the growth of overlayers. Yet no experimental techniques are capable of resolving that sturcture. Ab initio calculations of step structures on metal oxides are complex and have not been reported to date. By considering both the ionic and covalent components of interatomic bonding in metal oxides, we have developed a method of predicting the relative stability of different step structures.@footnote 1@ Fe@sub 3@O@sub 4@ (magnetite) is a ferrimagnetic metal that is of interest as substrate for growing complex oxides and for spintronics applications. Our STM observations on Fe@sub 3@O@sub 4@ (100) surfaces show step edges along both [110] and [1-10] directions; the step edges are found to be straight for steps heights of 4.2 ± 0.3 Å, but alternating smooth and jagged for step heights of 2.1 ± 0.2 Å. The straight (jagged) step edges are parallel (perpendicular) to the octahedral iron rows on the upper terrace. By evaluating the coordinative unsaturation of step-edge ions and the excess charge along a step, we show that steps parallel to the octahedral iron rows on the upper terrace are expected to be more stable than those perpendicular to them, in agreement with our STM observation. This step stability criterion is found to be independent of both terrace structure and step height. @FootnoteText@ *This research is partially supported by U.S. Department of Energy Grant No. DE-FG02-00ER45844, NSF Equipment Grant No. DMR-0075824, and NSF Grant MRSEC DMR-0520495.@footnote 1@V.E. Henrich and S.K. Shaikhutdinov, Surf. Sci. 574, 306 (2005).