Curie temperature for perovskite.

[lokanath patra]

Can I calculate curie temperature for perovskite compounds like BiFeO3 or BiCoO3. Is it possible to provide some example input files.

Thank you.

[Luke Elliott]

Hi Lokanath,

I have previously attempted to model the perovskite TbMnO3 using VAMPIRE, the issues I ran into mainly related to the complex anisotropy of the material. It is definitely possible to model perovskites though. In calculating the Curie temperature, you will need to choose a property to track as the cycloidal spin structure rules out the mean magnetisation length which is commonly used in VAMPIRE and I would suggest the chirality of the cycloid as your property. Please note chirality is not currently included in VAMPIRE and you will need to perform some analysis on your spin outputs. You will also need to create a Unit Cell File to enumerate the atom positions and interactions in your unit cell. In my work I generated this file using Python and the Mantid project libraries (http://docs.mantidproject.org/v3.9.0/api/python/index.html),

Your interactions will need to consider both isotropic and anisotropic components, these can be provided in the unit cell file as a tensor exchange with off-diagonal components giving the anisotropic exchange. I have included an annotated version of my final unit cell file as an example for structure, as well as the unit cell file specification. The unit cell file is specified in the input file as material:unit-cell-file=<unit cell file>.

Hope this helps a little,
Luke