Doubt about creating unit cell of multiple elements

[Somnath Jana]

I want to create an unit cell of two magnetic elements and an isotropic exchange interaction between them. So in total there will be three different exchange interaction strengths, say, a, b and c as follows.

material[1]:exchange-matrix[1]=a

material[1]:exchange-matrix[2]=b

material[2]:exchange-matrix[1]=b

material[2]:exchange-matrix[2]=c

If I understood it right, I need to provide a .ucf file to provide the atomic positions of the two elements. But the .ucf file also contains interactions according to the manual as follows.

Interactions n exctype, id i j dx dy dz Jij

But since, this is complicated to write, can I simply skip this part in the .ucf file and write in the material file as above?

Thank you.

[Somnath Jana]

Hi,

I might have misunderstood how to define the exchange matrix in the material file. Let me rephrase my question.

I'm trying to calculate the Curie temperature for a binary ferromagnetic alloy, such as CoPt. There are different exchange interactions between Co-Co, Co-Pt, and Pt-Pt. I want to perform this calculation for both an ordered crystalline structure and a disordered crystalline structure.

Could you please clarify how to define the exchange parameters for such a scenario? Any guidance or links to relevant resources would be greatly appreciated.

Thank you for your help.

Somnath

[gabo...@gmail.com]

can I simply skip this part in the .ucf file and write in the material file

At [1], you should see you can select between normalized or non-normalized exchange values in the ucf file.

When using the normalized, you need the exchange-matrix in the mat file.  The post at [2] might be of interest to you.

Your approach of using a ucf for an ordered crystalline structure seems to be a good one to me.

For the disordered, maybe the random alloy webpage can be helpful to you.  It should be at [3].

[1] https://groups.google.com/g/vampire-users/c/tZLKjnZbjFY/m/MIv0gbMIBAAJ

[2] https://groups.google.com/g/vampire-users/c/k96BaOK3zq4/m/30c5__JSAAAJ

[3] https://vampire.york.ac.uk/tutorials/system-generation/random-alloy/

Kind Regards,

Gavin

VAMPIRE user