Seeking help on applying a 1ns excitation pulse within a 15ns simulation run

[JEWELL KAYCEE]

Hi everyone,

I am looking for some guidance on a specific simulation setup. I would like to excite spin waves in my sample using a pulse that lasts for only 1 ns, but I need to observe the dynamic evolution of the magnetization over a total duration of 15 ns (i.e., Run(15e-9)).

Specifically, I am using a sinc pulse defined as:

0.001sinc(2*pi*15e9*(t-t0))

My goal is to have this dynamic field active only for the first 1 ns, while the entire system continues to evolve for the remaining 14 ns. Does anyone know the best way to implement this "time-gated" excitation in Mumax3?

Any help or suggestions would be greatly appreciated. Thank you very much for your time and assistance!

Best regards,

Jewell kaycee

[Josh Lauzier]

Hi,

You can do this as something like (assuming the excitation is in x and the bias field is in z. you can tweak this):

B_ext=vector( 0.001*sinc(2*pi*15e9*(t-t0)),0,B_dc)

run(1e-9)

B_ext=vector(0,0,B_dc)

run(14e-9)

That said, keep in mind that you're just going to be cutting off the edges of the sinc pulse, which is already very localized. For instance, plotting your pulse with t0=1e-9 (this t0 is too large if you're cutting off at 1e-9, I just picked it for the visual) looks something like:

Turning off the field at say t=2e-9 just cuts off the small wiggles past the red line. For smaller t0, the peak will be shifted closer to 0 and more of the early part of the signal gets cut off on the left.

Best,
Josh L.