FMR Frequency Plot

[gabo...@gmail.com]

I ran a VAMPIRE calculation that is hopefully simplified for illustrating a FMR frequency plot.  Should others be interested in it, the terminal steps are below and files are attached.  Feel free to provide any corrections if you find errors with it and modified it as needed for more complex FMR calculations. 

username@computername:~/Desktop/TM$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 24.04.1 LTS
Release: 24.04
Codename: noble
username@computername:~/Desktop/TM$ ls -l
total 20
-rwxr-xr-x 1 username username 887 Sep 24 23:54 fft.py
-rw-r--r-- 1 username username 705 Sep 24 23:08 input
-rw-r--r-- 1 username username  97 Sep 24 23:12 plotFreqFFT
-rw-r--r-- 1 username username 119 Sep 24 23:13 plotTimeM
-rw-r--r-- 1 username username 454 Sep 24 17:44 TM.mat
username@computername:~/Desktop/TM$ vampire-serial
                                                _          
                                               (_)        
                    __   ____ _ _ __ ___  _ __  _ _ __ ___
                    \ \ / / _` | '_ ` _ \| '_ \| | '__/ _ \
                     \ V / (_| | | | | | | |_) | | | |  __/
                      \_/ \__,_|_| |_| |_| .__/|_|_|  \___|
                                         | |              
                                         |_|              

                      Version 7.0.0 Dec 27 2023 21:29:33

             Git commit: fd9de813cab95bc2b2837122bd03f0238a5d2d76

  Licensed under the GNU Public License(v2). See licence file for details.

  Developers:   Richard F L Evans, Sarah Jenkins, Andrea Meo,
                Daniel Meilak, Andrew Naden, Matthew Ellis,
                Oscar Arbelaez, Sam Morris, Rory Pond, Weijia Fan,
                Phanwadee Chureemart, Pawel Sobieszczyk, Joe Barker,
                Thomas Ostler, Andreas Biternas, Roy W Chantrell,
                Wu Hong-Ye, Razvan Ababei, Sam Westmoreland,
                Milton Persson
 
                Compiled with:  GNU C++ Compiler
                Compiler Flags:

  Vampire includes a copy of the qhull library from C.B. Barber and The
  Geometry Center and may be obtained via http from www.qhull.org.

================================================================================
Tue Sep 24 23:56:29 2024
================================================================================
Initialising system variables
Creating system
Generating neighbour list..........done!
Copying system data to optimised data structures.
Using generic/normalised form of exchange interaction with 48 total interactions.
Number of atoms generated: 2700
Starting Simulation with Program fmr...
Simulation run time [s]: 2.17081
Simulation ended gracefully.
username@computername:~/Desktop/TM$ gnuplot --persist plotTimeM
username@computername:~/Desktop/TM$ python3 fft.py
username@computername:~/Desktop/TM$ gnuplot --persist plotFreqFFT

Best Regards,

Gavin

VAMPIRE user

[Charlie]

Is this with a fmr field pulse ? 

[Charlie Freeman]

Let me clarify. Have you modified the source code to apply a sinc pulse instead of the usual sine wave fmr field to do this ? I have been trying to do this myself and had some success, but still having issues with it. 

Charlie

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[gabo...@gmail.com]

Yes, I used "sim:program = fmr" & sim:enable-fmr-field and followed posts [1-3] to add sim:fmr-field-strength, sim:fmr-field-frequency, and sim:fmr-field-unit-vector.

Though, in the input file I previously attached, you should see I chose different values in my case of:

sim:fmr-field-strength = 0.001 !T
sim:fmr-field-frequency = 0.7 !GHz
sim:fmr-field-unit-vector = 0.001,0.999,0

[1] https://groups.google.com/g/vampire-users/c/wPiqmshWN-Q/m/48YFTxZ8BQAJ

[2] https://groups.google.com/g/vampire-users/c/-9dcWgf9eF4/m/hKyRyTY9CwAJ

[3] https://groups.google.com/g/vampire-users/c/or3XuSr_rxI/m/rtvD1b1OAQAJ

Kind Regards,

Gavin

VAMPIRE user

[gabo...@gmail.com]

No, I did not modify the source code.  To get the damped sinusoid, it seemed to help when I changed the damping-constant.  During one of my attempts, I had a damping constant of 0.002. 

In the previous post at (1) that has the plot of the damped sinusiod that had an attached material file, you should see though that it was changed in TM.mat to:

 material[1]:damping-constant=0.1

(1) https://groups.google.com/g/vampire-users/c/s8xhDaomocY/m/lFdhiVQfBgAJ

Kind Regards,

Gavin

VAMPIRE user

TimeM.png

[AMRENDRA KUMAR]

Dear Gavin,

I hope this message finds you well.

I wanted to reach out to see if you would be interested in collaborating on a ferromagnetic resonance (FMR) program for standard ferromagnets such as NiFe, which have been well studied using micromagnetic simulators like MuMax3 (I am also familiar with Mumax3).

I’ve conducted some simulations and encountered a few challenges that I believe we could resolve together. If you're open to it, we could meet to work on the project, and potentially publish the code for a better understanding of FMR using Vampire.

Please let me know if you’re interested in exploring this further.

Best regards,
Amrendra Kumar