Iron oxides are among the most abundant compounds on Earth and have consequently been studied and used extensively in industrial processes. Despite these efforts, concrete understanding of some of their surface phase structures has remained elusive, in particular the oxidized α−Fe2O3(0001) hematite surface. We detail an optimized recipe to produce this phase over the entire hematite surface and study the geometrical parameters and composition of its complex structure by means of atomically resolved microscopy, electron diffraction and surface-sensitive spectroscopies. We conclude that the oxidized α−Fe2O3(0001) surface is terminated by a two-dimensional iron oxide with structure, lattice parameters, and orientation different from the bulk substrate. Using total-energy density functional theory for simulation of a large-scale atomic model, we identify the structure of the surface layer as antiferromagnetic, conductive 1T−FeO2 attached on half-metal terminated bulk. The model succeeds in reproducing the characteristic modulations observed in the atomically resolved images and electron diffraction patterns.
@article{arxiv.1811.09996,
title = {Identification of two-dimensional $FeO_2$ termination of hematite ${\alpha}-Fe_2O_3(0001)$ surface},
author = {Jesús Redondo and Petr Lazar and Pavel Procházka and Stanislav Průša and Jan Lachnitt and Benjamín Mallada and Aleš Cahlík and Jan Berger and Břetislav Šmíd and Pavel Jelínek and Jan Čechal and Martin Švec},
journal= {arXiv preprint arXiv:1811.09996},
year = {2019}
}