Molecular dynamics simulation of magagnetic thin film and processing

Abstract

Simulation methods for materials and processing can be categorized into different scales, ranging from continuum methods that deal with mesoscale or macroscale phenomena to atomistic methods that capture the behavior of individual atoms or molecules. Continuum methods utilize numerical techniques such as partial differential equations (PDE) to solve problems at the device geometry scale, assuming homogenous material properties and smooth geometries. However, to fully understand the macroscopic properties and behavior of materials, it is essential to consider the microscopic structure and interactions of atoms and molecules. Molecular dynamics (MD) provides a way to model materials at the molecular level, accounting for the behavior and dynamics of individual atoms or molecules. Classical MD is a popular atomistic method that calculates forces and motions of atoms based on interatomic potentials derived from quantum mechanics methods like Density Functional Theory (DFT). The accuracy of MD simulations relies on the quality of these potentials, which should accurately capture the relevant physical and chemical effects.Recently, reactive MD methods like ReaxFF force field have been developed to model complex chemical reactions and transformations, including bond breaking and formation. By employing atomistic simulations, researchers can gain valuable insights into material properties and behaviors that bridge the gap between microscopic and macroscopic scales. In this dissertation, both classic and reactive MD models were developed to address the challenges for the materials science and engineering in magnetic recording media material, L10-FePt, and rare-earth-free permanent magnetic materials such as α"-Fe16N2.