MuMax3-How-To

Installation, scripting, & data generation demo of computational micro and nanomagnetism in MuMax3. Formed & written by Onri Jay Benally.

---

---

Main MuMax3 website: (https://mumax.github.io/index.html)

Uses code heavily-modified for clarity, inspired from: (https://github.com/mumax/3) & (https://mumax.github.io/examples.html)

Examples computed in this repository were performed on an Nvidia (RTX 4070 Ti Super) GPU, connected externally (via a Thunderbolt 4 to PCIe x16 adapter) to a Microsoft Surface Pro 8, later upgraded to a Surface Pro 10. If you are curious about this kind of GPU-accelerated computing setup, then it is best to make sure your Windows machine is Thunderbolt 4 compatible or greater.

Some Google Colab Notebooks
Run MuMax3 on the Cloud
Example of Data Imported From MuMax3 - Hysteresis Loop by Onri

How to Install & Run MuMax3 by Onri
Video Tutorial on How to Install MuMax3 Step-by-Step
Video Example of Onri's MuMax3 Hysteresis Plots in Python
Example MuMax3 Script in TXT Format
Video Animation of Magnetic Orders
Explanation of Hysteresis Curves & Coercivity
Micromagnetism Overview

---

If MuMax3 is installed already, start the GUI by typing the following 2 lines into a non-admin command prompt or non-admin PowerShell:

cd <directory_to_your_MuMax3_file>

mumax3 -i <your_MuMax3_TXT_file_name.txt>

Note: MuMax3 scripts can be written as TXT file types. The above script will load and automatically run the script into a browser.

Online OVF file type visualization: (https://mumax.ugent.be/mumax-view). While using the viewer, you can load multiple OVF files to play an animation of the magnetization frame capture.

---

Magnetic Conversion Table

Quantity	Symbol	Conversion
Field	$H$	$\dfrac{\mathrm{Oe}}{\mathrm{A}\cdot\mathrm{m}^{-1}}=\dfrac{10^{3}}{4\pi}=79.6$
Flux	$\Phi$	$\dfrac{\mathrm{Mx}}{\mathrm{Wb}}=\dfrac{\mathrm{Mx}}{\mathrm{V}\cdot\mathrm{s}}=10^{-8}$
Flux density	$B$	$\dfrac{\mathrm{G}}{\mathrm{T}}=\dfrac{\mathrm{G}}{\mathrm{Wb}\cdot\mathrm{m}^{-2}}=10^{-4}$
Magnetic moment	$m$	$\dfrac{\mathrm{emu}}{\mathrm{A}\cdot\mathrm{m}^{2}}=\dfrac{\mathrm{erg}\cdot\mathrm{Oe}^{-1}}{\mathrm{A}\cdot\mathrm{m}^{2}}=\dfrac{10,\mathrm{A}\cdot\mathrm{cm}^{2}}{\mathrm{A}\cdot\mathrm{m}^{2}}=\dfrac{\mathrm{emu}}{\mathrm{J}\cdot\mathrm{T}^{-1}}=10^{-3}$
Magnetization per unit volume	$M$	$\dfrac{\mathrm{emu}\cdot\mathrm{cm}^{-3}}{\mathrm{A}\cdot\mathrm{m}^{-1}}=\dfrac{\left(\mathrm{erg}\cdot\mathrm{Oe}^{-1}\right)\cdot\mathrm{cm}^{-3}}{\mathrm{A}\cdot\mathrm{m}^{-1}}=10^{3}$
Magnetization per unit mass	$\sigma$	$\dfrac{\mathrm{emu}\cdot\mathrm{g}^{-1}}{\left(\mathrm{A}\cdot\mathrm{m}^{2}\right)\cdot\mathrm{kg}^{-1}}=\dfrac{\left(\mathrm{erg}\cdot\mathrm{Oe}^{-1}\right)\cdot\mathrm{g}^{-1}}{\left(\mathrm{A}\cdot\mathrm{m}^{2}\right)\cdot\mathrm{kg}^{-1}}=1$
Magnetic polarization	$J$	$\dfrac{\mathrm{emu}\cdot\mathrm{cm}^{-3}}{\mathrm{T}}=\dfrac{\left(\mathrm{erg}\cdot\mathrm{Oe}^{-1}\right)\cdot\mathrm{cm}^{-3}}{\mathrm{T}}=10^{3}\mu_{0}=4\pi\cdot10^{-4}$
Volume susceptibility	$\chi_{\mathrm{v}}$	$\dfrac{\left(\mathrm{emu}\cdot\mathrm{Oe}^{-1}\right)\cdot\mathrm{cm}^{-3}}{\left(\mathrm{A}\cdot\mathrm{m}^{2}\right)\cdot\left(\mathrm{A}\cdot\mathrm{m}^{-1}\right)^{-1}\cdot\mathrm{m}^{-3}}=4\pi$
Mass susceptibility	$\chi_{\mathrm{m}}$	$\dfrac{\left(\mathrm{emu}\cdot\mathrm{Oe}^{-1}\right)\cdot\mathrm{g}^{-1}}{\left(\mathrm{A}\cdot\mathrm{m}^{2}\right)\cdot\left(\mathrm{A}\cdot\mathrm{m}^{-1}\right)^{-1}\cdot\mathrm{kg}^{-1}}=4\pi\cdot10^{-3}$
Permeability	$\mu=\dfrac{B}{H}$	$\dfrac{\mathrm{G}\cdot\mathrm{Oe}^{-1}}{\mathrm{T}\cdot\left(\mathrm{A}\cdot\mathrm{m}^{-1}\right)^{-1}}=\mu_{0}=4\pi\cdot10^{-7}$
Relative permeability (SI)	$\mu_{\mathrm{r}}$	$\dfrac{\mu_{\mathrm{SI}}}{\mu_{0}}=\mu_{\mathrm{r}}=\mu_{\mathrm{cgs}}$
Energy density	$W$	$\dfrac{\mathrm{erg}\cdot\mathrm{cm}^{-3}}{\mathrm{J}\cdot\mathrm{m}^{-3}}=0.1$
Demagnetizing factor	$N$	$\dfrac{N_{\mathrm{cgs}}}{N_{\mathrm{SI}}}=4\pi$
Energy product	$(BH)$	$\dfrac{\mathrm{G}\cdot\mathrm{Oe}}{\mathrm{T}\cdot\left(\mathrm{A}\cdot\mathrm{m}^{-1}\right)}=\dfrac{\mathrm{G}\cdot\mathrm{Oe}}{\mathrm{J}\cdot\mathrm{m}^{-3}}=4\pi\cdot10^{1}=126$ $\dfrac{\mathrm{MG}\cdot\mathrm{Oe}}{\mathrm{kJ}\cdot\mathrm{m}^{-3}}=4\pi\cdot10^{-2}=0.126$

Mx = maxwell, G = gauss, Oe = oersted, Wb = weber, V = volt, s = second, T = tesla, m = meter, A = ampere, J = joule, kg = kilogram, g = gram, cm = centimeter, with $\mu_0=4\pi\times10^{-7}$.

---

Below is an example of a Hysteresis loop plotted in Python from the MuMax3 computation, provided by one of my examples above:

Magnetic material visualization example ran in MuMax3:

Magnetic geometry (300 nm x 100 nm x 3 nm) visualization in 3D using MuMax View in the browser:

More examples:

---

---

Related Animated Videos for Your Reference:
Tunnel Effect
Quantum Difference Between Metals & Insulators
Magnetic Orders
Frustrated Magnets
Bose-Einstein Condensation
Nuclear Magnetic Resonance (NMR)
Transmission Electron Microscopy
Scanning Tunneling Microscopy
Scanning Electron Microscopy
Atomic Force Microscopy