Spin wave dispersion relation simulation with demagnetization field.

[Ricky]

Hello, everyone. I hope you are all having a great summer. I have a question about how to simulate magnon band structures with enabled demagnetization. 

The code that I am using can be found in the mumax3 workshop google colaboratory session (Much appreciate for this great workshop btw!).

Workshop: https://mumax.ugent.be/mumax3-workshop/

Code: https://colab.research.google.com/github/JeroenMulkers/mumax3-tutorial/blob/master/postprocessing.ipynb

Using the code, I have been trying to get a dispersion relation with enabled demagnetization field, but I do not see any signal in the result. I tried a couple of things like adding cells along x and z directions or orienting the bias field, but it did not work.

It would be great if you can give me some advice to resolve this issue.

Thanks in advance!

[Felipe Garcia]

Hi Ricky,

If you enable Demag with your parameters then the system is in-plane. Therefore, one has to increase the field to put it in the saturated state along Z. Maybe, 1.25 T should be enough. Otherwise, your rf field is parallel to the magnetization and you will not get the standard results.

Moreover, several things have to be checked. One has  to estimate the maximum frequency of the sine cardinal so that it matches the range of frequencies in your system. Also, one has to compare with the proper dispersion relation, because now it is no longer the simple expression of the tutorial.

Best regards,

Felipe

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[Ricky]

Thanks for the reply Felipe.

I realized that the system did not have strong enough external field to saturate the thin film. I applied 1.25 T and now I get clean dispersion relation for the FVMSW even with the dipolar interaction.

Thanks again and have a great weekend.

Best,

Ricky.