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Here, we use spin-polarized density functional theory to describe the surface reconstructions formed when the Cr(001) surface is exposed to nitrogen. Our primary goal is to clarify the atomic structure of the N induced c(2x2) Cr(001) reconstruction and to study its properties. After analyzing the relative stability of several models with a ½ monolayer of N atoms on the surface, it was found that only two models were stable for different growth conditions. The first stable model shows two N atoms (per cell) adsorbed on hollow sites following a diagonal pattern. In the second, N atoms replace Cr atoms ofmore » the first monolayer, and after optimization, they end up in almost second layer positions. To compare with scanning tunneling microscopy experiments, simulated STM images, using the Tersoff-Hamann approximation, were obtained. Our two models can explain the two different c(2x2) Cr(001) reconstructions observed experimentally. The magnetic properties, such as magnetic moments and alignments, are discussed compared with experimental values.« less

Spin-polarized first-principles total energy calculations have been performed to study the structural, electronic and magnetic properties of Mn₃N₂(0 0 1) surfaces. It is found that three surface terminations are energetically stable, in agreement with previous scanning tunneling microscopy experiments that have found three different electronic contrasts in their images. It is also found that in all three cases, the topmost layer has a MnN stoichiometry. Density of states calculations show a metallic behavior for all the stable structures with the most important contribution close to the Fermi level coming from the Mn-d orbitals. Finally, our Tersoff–Hamann scanning tunneling microscopy simulationsmore » are in good agreement with previous experimental results.« less