Fidimag – A Finite Difference Atomistic and Micromagnetic Simulation Package

Abstract

Fidimag is an open-source scientific code for the study of magnetic materials at the nano- or micro-scale using either atomistic or finite difference micromagnetic simulations, which are based on solving the Landau-Lifshitz-Gilbert equation. In addition, it implements simple procedures for calculating energy barriers in the magnetisation through variants of the nudged elastic band method. This computer software has been developed with the aim of creating a simple code structure that can be readily installed, tested, and extended. An agile development approach was adopted, with a strong emphasis on automated builds and tests, and reproducibility of results. The main code and interface to specify simulations are written in Python, which allows simple and readable simulation and analysis configuration scripts. Computationally costly calculations are written in C and exposed to the Python interface as Cython extensions. Docker containers are shipped for a convenient setup experience. The code is freely available on GitHub and includes documentation and examples in the form of Jupyter notebooks. Funding Statement: We acknowledge financial support from EPSRC’s Centre for Doctoral Training in Next Generation Computational Modelling, (EP/L015382/1), EPSRC’s Doctoral Training Centre in Complex System Simulation (EP/G03690X/1), CONICYT Chilean scholarship programme Becas Chile (72140061), Horizon 2020 European Research Infrastructure project OpenDreamKit (676541), National Natural Science Foundation of China (11604169), and the Gordon and Betty Moore Foundation through Grant GBMF #4856, by the Alfred P. Sloan Foundation and by the Helmsley Trust.

Keywords

• Python
• Cython
• finite differences
• nanomaterials
• micromagnetism
• Landau-Lifshitz-Gilbert
• LLG
• spin-transfer torque
• micromagnetic simulations
• domain walls
• skyrmions
• vortex
• vortices