Fractional magnetic charges and channeling of Faraday lines by disclinations in artificial spin ice
Data files
Jan 31, 2025 version files 49.64 MB
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MFM_Data.zip
49.52 MB
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Mumax3_Data.zip
110.49 KB
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README.md
4.13 KB
Abstract
We have studied the magnetic moments of artificial spin ice arrays of nanomagnets in both undistorted square arrays and in arrays with a topological defect induced by a single disclination. We confirm that the disclination induces global, macroscopic changes in the low-energy collective states of the nanomagnet moment configuration. Specifically, the disclination leads to Faraday lines of effective magnetic flux that run from the center all the way to the edge of the arrays. Moreover, the geometric deformation, induced by the topological defect, curves the geometry such that these Faraday lines are channeled preferentially by the arrays’ curved geometry. Our results demonstrate how the intentional combination of topology and geometry can be designed to control magnetic charges and the flow of local magnetization and thus manipulate associated collective excitations.
README: Fractional magnetic charges and channeling of Faraday lines by disclinations in artificial spin ice
[Access this dataset on Dryad](DOI: 10.5061/dryad.3ffbg79vh)
This dataset contains raw magnetic force microscopy (MFM) images and results of micromagnetic simulations. Codes for analyzing data and creating the micromagnetic simulations are also included.
Description of the data and file structure
This data is separated into folders that contain data and code.
There are two data folders, "Mumax3 Data" and "MFM Data", containing the results of the micromagnetic simulations and magnetic force microscopy images, respectively.
Organization of "MFM Data"
- 2 subfolders "AH-D-2_S8_A1" and "AH-D-2_S8_A2" which represent data taken from the same sample but after a new anneal for each data set.
- The .csv file "AH-D-2_S8" is a master file that connects the image numbers in "AH-D-2_S8_AX" to the specific sample that is represented.
- For example, consider image "Phase961.jpg" in the folder "AH-D-2_S8_A2". The .csv file indicates this image is of a disclination of size N=21 with lattice spacing a = 280.
- Important conventions in the .csv file:
- The sample used has 16 total copies of a given disclination with a certain N and lattice spacing (a). The letter identifier indicates which copy of the disclination array is measured. Specifically disclination arrays are arranged in a 4 x 4 grid, labelled in alphabetical order, starting from the top left and continuing to the right.
- The next column indicates if the image could be successfully transcribed from a black and white image to an actual data file. if "proc" is written, this procedure was successful and this image was able to be used in the full data analysis. If anything else was written (or nothing was written), this image was not able to be used in the full data analysis.
- Folders "AH-D-2_S8_AX" first have all the MFM images labelled "PhaseXXXX.jpg". These folders have a subfolder called "processed" which contain csv files that have used image recognition on the images to get spin values. Files of the naming convention "dataXXXX.csv" belong to disclination samples, while "XXXXoutput.csv" belong to square samples. This contains another subfolder "files for batch programs" which are the results of running the aforementioned data through the "Initial" programs listed in "Analysis Code - Undistorted" for convenience.
"Mumax3 Data" contains csv files that are the processed results of the micromagnetic simulations (after running Mumax3 then using "rotanlyze"). These can be processed by the code "Initial Mumax Processing v2" in the "Analysis Code - Undistorted" folder.
The naming conventions vary for the undistorted and distorted cases. For the undistorted case: nXaYYY.csv where X is the size of the disclination (e.g. 21) and YYY is the lattice spacing (e.g. 280)
For the distorted case: all included files are at a lattice spacing of a = 280. The values following a and b represent the distortion parameters alpha and beta used in the manuscript. In this case N21a1_01b0_05 represents data for N = 21, lattice spacing = 280, alpha = 1.01, and beta = 0.05
Code/Software
There are three folders containing code, "Mumax3 Code", "Analysis Code - Distorted", and "Analysis Code - Undistorted".
- "Mumax3 Code" contains MATLAB code for generating scripts that can then be run using the Mumax3 software. It also contains code for doing some basic analysis of results and modification into data formats that can be read in by programs in the Analysis Code folders. This folder contains a README.md file which details how to use the code in folder
"Analysis Code - Undistorted" contains code responsible for analyzing undistorted disclination arrays as well as square arrays. This folder contains a README.md file which details how to use the code in folder
"Analysis Code - Distorted" contains code responsible for analyzing distorted disclination arrays as well as functions for the Boltzmann calculation done in the manuscript. This folder contains a README.md file which details how to use the code in folder
Methods
The experimental data in this work was collected via magnetic force microscopy (MFM), which provides black and white images indicating the magnetization of individual nanoislands in the measured arrays. The direction of each island can be categorized as +1 or -1 via image recognition and then analyzed by the included codes to recreate the work of the main manuscript.
The simulation data in this work was produced via the software Mumax3. The scripts to run this were produced by included MatLab files.