Clarification on Non-adiabatic Factor in Zhang Li torque

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Shyamali

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Aug 29, 2025, 10:19:51 AM (13 days ago) Aug 29
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Hi,

I want to clarify whether the two terms appear in Mumax3 papers in context of Slonczewski and Zhang Li torque, denoted by the same parameter ξ  have the same meaning also for both the mechanisms.
It will be really helpful if any of you share your thoughts on this. Looking forward to hearing from you

Thanks in advance,
Mani 
SlonczewskiTorque.png
ZhangLiTorque.png

Subham Das

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Aug 29, 2025, 12:18:39 PM (13 days ago) Aug 29
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This parameter, ξ  is only for the Zhang-Li torque. If you see the journal "The design and verification of mumax3", you will see that the Slonczewski terms don't have  ξ .

Shyamali

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Aug 29, 2025, 12:35:34 PM (13 days ago) Aug 29
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Thank you for the reply. PFA  the article I am referring to understand Slonczewski torque. There ξ term is introduced while explaining 'Parameters for spin-transfer torques'. I want to confirm whether that ξ have the same meaning as in case of Zang Li torque mentioned in the paper  'The design and verification of mumax3 '.

Regards,
Mani



TutorialMumax3.pdf

Josh Lauzier

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Aug 29, 2025, 9:06:49 PM (13 days ago) Aug 29
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Hi,

In that usage, the Slonczewski torque is being repurposed to mimic a spin orbit torque. While there is no built in form for SOT in mumax, it turns out you can map it to behave like a Slonczewski STT. This is convenient because reusing the built-in STT will be faster than just doing a full custom field.

It is not quite the same meaning- for SOT, it is the ratio between the field-like and damping-like torques. For Zhang-Li, it is a measure of nonadiabicity. A Slonczewski-type torque (either actual Slonczewski, or SOT reusing Slonczewski implementation) will not behave the same as Zhang-li type torques, and tuning that parameter will not have the same effect. You can think of it as similar in the sense of "in both cases, both types of torques have two different components, and this parameterizes the relative strength between the two". But how those two terms behave is very different for the different types of torque.

Best,
Josh L.

Shyamali

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Aug 30, 2025, 1:07:33 AM (12 days ago) Aug 30
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Thank you for your response.

Regards, 
Mani

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