Surface segregation in nanoparticles from first principles

Abstract

FePt nanoparticles are known to exhibit reduced L1${}_0$ order with decreasing particle size. The reduction in order reduces the magnetic anisotropy and the thermal stability of the direction of magnetization of the particle. The phenomenon is addressed by investigating the thermodynamic driving forces for surface segregation using a local (inhomogeneous) cluster expansion fitted to ab initio data which accurately represents interatomic interactions in both the bulk and surface regions. Subsequent Monte Carlo simulations reveal that first surface layer Pt segregation is compensated by Pt depletion in the second subsurface layer. This indicates that the core's ordered state is not affected by surface thermodynamics as much as previously thought. Thus, the weak ordering experimentally observed is likely not due to fundamental thermodynamic limitations but rather to kinetic effects.

References in corpus (6)

• The Effect of Lattice Vibrations on Substitutional Alloy Thermodynamics
• Temperature and particle size dependence of equilibrium order parameter of FePt
• The Evolution of Magnetism in Iron from the Atom to the Bulk
• Reduced carbon solubility in Fe nano-clusters and implications for the growth of single-walled carbon nanotubes
• Influence of Mo on the Fe:Mo:C nano-catalyst thermodynamics for single-walled carbon nanotube growth
• Monte Carlo simulation of equilibrium L1_0 ordering in FePt nanoparticles

Cited by in corpus (6)

• AFLOW: An automatic framework for high-throughput materials discovery
• icet - A Python library for constructing and sampling alloy cluster expansions
• A RESTful API for exchanging Materials Data in the AFLOWLIB.org consortium
• A high-throughput ab initio review of platinum-group alloy systems
• Construction and sampling of alloy cluster expansions -- A tutorial
• Predicting activation energies for vacancy-mediated diffusion in alloys using a transition-state cluster expansion