Mode profiles and their animations (movies)

This notebook will calculate the dispersion relation of a film with 50 nm thickness and permalloy material parameters.

The dispersion is computed for the Damon-Eshbach geometry, wave vector perpendicular to the ground magnetic state stabilized by an external static magnetic field of 20 mT.

First we import the TetraX package.

import tetrax as tx

Let’s create the 50 nm thick permalloy film…

py_film = tx.Sample(
    tx.geometries.layer.monolayer(50,2),
    name="Monolayer_mode_movie",
    geometry_type="layer")

py_film.material = tx.materials.permalloy

… and compute the dispersion with the applied external field:

py_film.mag = (1,0,0)
py_film.Bext = (20e-3,0,0)
spectrum = tx.experiments.eigenmodes(py_film,kmin=0,kmax=40e6,num_modes=5,num_cpus=-1,save_mode_profiles=True)

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First, we plot the dispersion, using the built-in plot() method:

spectrum.plot(n=[0,1], kscale='u', k=[0,40e6], fscale='G')

Show modes and animate them

The spectrum result object of the eigenmodes experiment has a built-in method show_mode, to visualize the modes od a given wave vector k, mode number n and azimuthal mode number m for axial geometries.

Most important options for the visualization and animation are:

- wave vector k=..., in [rad/m]
- mode number n=...
- mode number m=... # for axial geometries
- scaling the magnetization, scale=...,
- scaling the dynamical components, scale_mode=...
- with or without the equilibrium magnetization, on_equilibrium=True or False
- animated = True or False
- the requested periods, periods=...
- frames_per_period=...
- frames per seconds, fps=...

• Below you find an example for a Daemon-Eshbach surface mode, namely the mode with n=1 for k=10 (rad/µm), choosing 10 periods, 30 frames per seconds, etc…

• This mode, as expected, is localized mostly to one of the surfaces.

spectrum.show_mode(k=10e6,n=1,periods=10,animated=True,scale=10,fps=30,scale_mode=2)

/Users/attilak/micromag/tetrax-tests/fresh_environement_test/venv/lib/python3.13/site-packages/traittypes/traittypes.py:97: UserWarning:

Given trait value dtype "float32" does not match required type "float32". A coerced copy has been created.