Excitation of Spin waves of definite handedness

[Diksha Prajapati]

Hello everyone,
I was wondering if it is possible to excite spin waves with a definite handedness (left- or right-handed) in MuMax3 — analogous to how left- and right-handed circularly polarized light can be generated in optics.  

With regards,

Diksha

[Diksha Prajapati]

Could anyone please help me with this?

[Антон Луценко]

Hi Diksha,

There is no direct correspondence of polarization of EM waves in spin waves. Thus, this is not a question related to MuMax but rather to the physics of spin waves. 

Since a single spin precession direction is defined by the LLG equation, the spins in a "regular" spin wave in ferromagnets exhibit Larmor precession (if that is what you mean by handedness). The opposite precession direction can be observed in special cases: evanescent modes (https://link.aps.org/accepted/10.1103/PhysRevB.101.144430), vortex modes (https://arxiv.org/abs/1712.00681), some systems with STT (https://arxiv.org/abs/1807.09456) and PMA (https://arxiv.org/abs/2502.10085v1). They were also recently found in ferrimagnets ( https://doi.org/10.1038/s41563-020-0722-8 ). Even if you make a left-hand polarized oscillating field, you don't excite them in a regular FM or FiM, rather you can stop exciting them entirely at some combination of parameters (https://arxiv.org/abs/2202.00780).

Hope that helps!

[Diksha Prajapati]

Thank you so much for all the references.

With regards,

Diksha