This repository contains the micromagnetic simulation scripts for the publication Do Images of Biskyrmions Show Type-II Bubbles? by J. C. Loudon, A. C. Harrison, D. Cortes-Ortuno, M. T. Birch, L. A. Turnbull, A. Stefancic, F. Ogrin, E. Burgos-Parra, A. Campbell, H. Popescu, M. Beg, O. Hovorka, H. Fangohr, P. A. Midgley, G. Balakrishnan and P. D. Hatton

Simulations are based on the OOMMF code [1] and its Jupyter interface JOOMMF [2]

Simulation scripts are located in the sims/oommf folder, where there are different directories:

• bubble_lattice_A20pJm-1_mu0Ms648e-3_field-sweep: simulation of lattice of bubbles in a cuboid sample, starting from an array of hexagonally arranged dots with the out of plane magnetisation direction in the -z direction on a background with m_z=1

• bubble_lattice_A-sweep_mu0Ms-sweep_field-sweep: simulation of a lattice of bubbles by varying the exchange, saturation magnetisation and applied field. These simulations help to find a suitable range of magnetic parameters to stabilise bubbles and compare them to the experimental data

• film_random_A20pJm-1_mu0Ms648e-3: multiple simulations starting from different random initial configurations (random;y oriented spins)

• film_random_A20pJm-1_mu0Ms648e-3_field-sweep: (hysteresis-like) field sweep process starting from the random configurations obtained from film_random_A20pJm-1_mu0Ms648e-3. These simulations show the formation of spirals and different types of bubbles as the field is increased

• isolated_typeII_bubble_A20pJm-1_mu0Ms648e-3_field-sweep: simulation of isolated type-II bubbles in a cuboid sample to analyse their size and applied field range of stability. Simulations are performed for different cuboid sizes. See the images folder for different type-II bubble visualisations

Since simulations are based in OOMMF [2], the scripts are given as .mif text files. Makefiles are also provided, but tsome paths might require updating. Scripts assume you can run OOMMF using the oommf system variable/command.

Notebooks analysing/processing the data from the simulations are provided in the notebooks directory

An interactive example is given in the main folder to simulate a type-II bubble

If you find this material useful please cite us:

@Misc{Cortes2019,
  author       = {David Cort{\'e}s-Ortu{\~n}o and James C. Loudon and Marijan Beg and Ondrej Hovorka and Hans Fangohr},
  title        = {{Supplementary data for: Do Images of Biskyrmions Show Type-II Bubbles?}},
  howpublished = {Zenodo doi:10.5281/zenodo.1420447. Github: https://github.com/davidcortesortuno/paper_biskyrmions_bubbles},
  year         = {2019},
  doi          = {10.5281/zenodo.1420447},
  url          = {https://doi.org/10.5281/zenodo.1420447},
}

[1] M. J. Donahue and D. G. Porter, OOMMF Users Guide, Version 1.0, Tech. Rep. (National Institute of Standards and Technology, Gaithersburg, MD, 1999).

[2] M. Beg, R. A. Pepper, and H. Fangohr, User interfaces for computational science: A domain specific language for OOMMF embedded in python. AIP Advances 7, 056025 (2017), https://doi.org/10.1063/1.4977225.