Clustering and Anisotropy due to Step-Edge Segregation in vapor deposited CoPt3: Calculation and Simulation

Published

October 16, 2008

Author(s)

Brian B. Maranville, M Scherman, F Hellman

Abstract

An atomistic mechanism is proposed for the creation of structural anisotropy and consequent large perpendicular magnetic anisotropy in vapor deposited films of CoPt3. Energetic considerations of bonding in Co-Pt suggest that Co segregates to step edges due to their low coordination, for all film orientations, while Pt segregates to the two low index surfaces. Coalescence of islands during growth cause these Co-rich step edges to become flat thin Co platelets in a Pt rich matrix, giving rise to the experimentally observed magnetic anisotropy. This proposed model is tested with kinetic Monte Carlo simulation of the vapor deposition growth. A tight-binding, second-moment approximation to the potential is used to calculate the potential landscape for surface atoms, giving an Arrhenius-like activation model of surface motion. Results for individual layers show Co step edge segregation. The simulated as-grown films show an asymmetry in Co-Co bonding between the in-plane and out-of-plane directions, in good agreement with experimental data, and a strong correlation with Co edge segregation on the surface. The growth temperature dependence found in the simulations is strong and similar to that seen in experiments.

Citation

Physical Review B (Condensed Matter and Materials Physics)

Pub Type

Journals

Keywords

anisotropy, clustering, kinetic Monte Carlo simulation, step-edge segregation

Citation

Maranville, B. , Scherman, M. and Hellman, F. (2008), Clustering and Anisotropy due to Step-Edge Segregation in vapor deposited CoPt₃: Calculation and Simulation, Physical Review B (Condensed Matter and Materials Physics) (Accessed December 10, 2024)