Unstable magnetisation after equilibration

[Peela baradwaj naidu]

Hello Vampire Users,
I am studying domain wall motion in CGT under temperature pulses and magnetic field pulses. I have written a 2 part program where I use domain program to create a simple domain wall and equilibrate it under finite temeprature and use this checkpoint to start a temperature pulse. however , I notice that my energy is equilibrated and flat before temperature pulse starts however my magnetisation sees large oscillations. i am attaching my program files. Can someone please advice why my magnetisation at t<0 is not flat.

[gabo...@gmail.com]

It looks like your material_automated.mat has a relatively small α, i.e.:

material[1]:damping-constant = 0.006

Have you tried increasing the α value to see if it dampens out the oscillations in the magnetization?  Have you also tried turning off the temperature pulses or setting temperature to 0, or turning off the magnetic field pulses to see if one of them perhaps could be significantly contributing to the oscillations?

The applet at (1) is rudimentary compared to VAMPIRE, but maybe it can help illustrate how a small α near zero can be more oscillatory in magnetization than that for a higher constant:

(1) https://demonstrations.wolfram.com/PrecessionOfMagnetizationUsingTheLandauLifshitzEquation/

Kind Regards,

Gavin

VAMPIRE user

[Peela baradwaj naidu]

Thanks for the reply Gavin,
I was under the impression that that the first part of the program where I equilibrate domain wall already has a high damping 0.8 so if i use that check point as a starting configuration when I restart and begin the second part I should not see much oscillations since the there is no B field applied until time t=0.