Saddle-point energies and Monte Carlo simulation of the long-range order relaxation in CoPt

TL;DR

This paper combines atomic-scale simulations using Molecular Dynamics and Monte Carlo methods to study vacancy-mediated relaxation and order-disorder transition in CoPt, revealing key energies and transition temperature.

Contribution

It introduces a new simulation approach with a Tight-Binding potential to evaluate saddle-point energies and study relaxation in CoPt.

Findings

Vacancy migration energy of 0.73 eV

Order-disorder transition temperature of 935 K

Simulation of long-range order relaxation

Abstract

We present atomic-scale computer simulations in equiatomic L1$_0$-CoPt where Molecular Dynamics and Monte Carlo techniques have both been applied to study the vacancy-atom exchange and kinetics relaxation. The atomic potential is determined using a Tight-Binding formalism within the Second-Moment Approximation. It is used to evaluate the different saddle-point energies involved in a vacancy-atom exchange between nearest-neighbour sites. The potential and the saddle-point energies have been used to simulate the relaxation of the long-range order in CoPt using a Monte Carlo technique. A vacancy migration energy of $0.73\pm 0.15 eV$ and an order-disorder transition temperature of 935 K have been found.