simple histeresis loops - Fe

[Juliana Zarpellon]

Hello Vampire users!

I'm new to Vampire, so to understand how it works, I decided to start with simple Fe hysteresis loops, with a material without boundaries.

I started with an external magnetic field applied in the [100] direction, and the curve I got was not symmetrical (there is a small "knee" in the return of the magnetic field). Then, I decided to try with the external magnetic field in the [110] and [111] directions, and the curves came out weird. I've attached the input, Fe.mat and output files, as some printouts of the hysteresis curves I got.

So, about this, I have a few questions:

1) In the input file, I asked for the output only 3 "responses": real time, applied field strength and magnetization, so why do I have 6 columns in my output file? What do they mean?

2) I understand that "column 3" represents magnetization (or M/Ms), so I plotted it against "column 2" (applied field) with the magnetic field in three different crystallographic directions: why are they so strange? Only the [100] direction is close to the expected curve, but it has a small "knee" in the return of the magnetic field... why is it there?

3) I plotted "column 4" against "column 2" (applied field) and noticed that "column 3" and "column 4" seemed to be symmetrical in the sense that in the interval where one of them goes down, the other goes up. So I decided to add these two columns and the result is that for the [110] and [111] directions the hysteresis looks better! But in the [100] direction the opposite happens. Why? Why does the sum seem to work?

4) In this sum, the hysteresis curves for the [110] and [111] directions look the same! This is not expected, since these directions are not both the axis of easy magnetization. Why is this happening?

Can anyone help me?

Sorry if the questions are too basic, but that's because I'm REALLY a beginner :)

Thanks a lot!
Juliana

[Gavin Abo]

Based on your input file, it looks like your 6 column output is the following.

Column 1: real-time simulation time in seconds.

Column 2: applied-field-strength (amplitude |H|) in Tesla.

Column 3: magnetisation unit vector x component m-hat_x.

Column 4: magnetisation unit vector y component m-hat_y.

Column 5: magnetisation unit vector z component m-hat_z.

Column 6: magnetisation length amplitude |m|.

The past post at [1] might be of interest to you (which I think elicited to Mi/Ms = m-hat_i*|m| with i = x, y, z).

[1] https://groups.google.com/g/vampire-users/c/eRk1_-iAw_Q/m/QbOuF-_0BQAJ

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