Atomistic simulation of Fe deposition and alloy formation on Pt substrates

Fe-Pt alloys are of significant importance toward future applications of high-density magnetic recording media. In this work, we apply the BFS method for alloys to study the energetic pathway for subsurface Fe-Pt alloy formation upon deposition of Fe atoms on Pt(1 0 0), Pt(1 1 1), and vicinal Pt(9 9 7) substrates. The simulation results indicate preference for Fe atoms to occupy sites in the Pt subsurface layers and form an ordered alloy phase upon deposition on a low-index Pt surface. This behavior results in Pt surface segregation leading to nucleation of 3D Pt islands. However, the energetics behind deposition of Fe on Pt(9 9 7) indicate that Fe atoms prefer decoration of Pt step edges prior to formation of the ordered Fe-Pt surface alloy, where the ordered alloy is observed to form at the edges of the monoatomic surface steps. In each case presented here, the results are in agreement with experiment, and the formation of a Fe-Pt subsurface alloy is explained by a simple analysis emerging from the competition between BFS strain and chemical energy contributions.