First Principles Calculations of the Energetic, Structural, Electronic, and Magnetic Properties of Fe/Ir(100) System

Although the Fe/Ir(100) system has been extensively investigated, contradictory conclusions were drawn from different experimental and theoretical studies about its magnetic ground state. In this work, density functional theory calculations are performed for the adsorption of Fe on the Ir(100) surface with different coverages to resolve this contradiction. The obtained adsorption energy decreases as the coverage increases, which reflects the effect of repulsive interaction between the adsorbates. Antiferromagnetic (AFM) configuration is found to be more stable than the ferromagnetic (FM) configuration for the 0.50 and 1.00 monolayer (ML) coverages. Fe atoms start to form a body centered cubic (BCC) structure, with the basis of a lattice parameter of Ir and have a pseudomorphic growth. The FM configuration is found to be more stable than the AFM configuration for Fe bilayer on Ir(100) surface with c/a ≈ 0.53, which predicts a BCC Fe precursor due to the small lattice mismatch between Fe and Ir surface. The electronic properties predict that the reactivity of Ir surface decreases beyond Fe coverage of 0.50 ML since the d band center of 5d Ir shifts to the left of Fermi energy as Fe coverage increases.