[Wien] elast for magnetic material + curie temp

[Fecher, Gerhard]

The Curie temperature can be roughly estimated from a comparison of the total energies of the ferromagnetic and the antiferromagnetic states.
For a better way please check our book Felser/Fecher Spintronics: From materials to devices published by Springer and in particular the chapter by Kübler Fecher Felser.
You will need to calculate the exchange coupling constants Jij either in real or in momentum space (Note that one form is found from the Fourier transformation of the other and vice versa).
The latter you can do with the non collinear spin code of Wien2k
see also: Kübler Fecher Felser, Understanding the trend in the Curie temperatures of Co2-based Heusler compounds:
Ab initio calculations; in Phys. Rev. B 76, 024414 (2007)
(Indeed, this method works also for Neel temperatures)

Before you try such things, be sure that you know very well what you are doing

Ciao
Gerhard

DEEP THOUGHT in D. Adams; Hitchhikers Guide to the Galaxy:
"I think the problem, to be quite honest with you,
is that you have never actually known what the question is."

====================================
Dr. Gerhard H. Fecher
Institut of Inorganic and Analytical Chemistry
Johannes Gutenberg - University
55099 Mainz
and
Max Planck Institute for Chemical Physics of Solids
01187 Dresden
________________________________________
Von: wien-bounces at zeus.theochem.tuwien.ac.at [wien-bounces at zeus.theochem.tuwien.ac.at] im Auftrag von Xavier Rocquefelte [xavier.rocquefelte at univ-rennes1.fr]
Gesendet: Donnerstag, 20. August 2015 10:08
An: A Mailing list for WIEN2k users
Betreff: Re: [Wien] elast for magnetic material + curie temp

About the Néel temperature, I know two main strategies:
- If you know an analytical formula which relates TN with J values (J: magnetic exchange parameters of your system) then you can estimate TN from DFT calculations. It will require the calculation of all the J's values of your system. Such a calculation of TN is possible for simple systems for which the analytical equation is known (one-dimensional Heisenberg magnetic system).
- In a more general case, you need to include the temperature fluctuation effects on your magnetic system.  To do this, you must go beyond DFT. For instance, doing Monte-Carlo calculations using DFT paramaters will allow you to estimate TN.
Cheers
Xavier


Lyudmila Dobysheva <lyuka17 at mail.ru> a écrit :

> 20.08.2015 07:28, Murugan Sundareswari ?????:
>> Is it possible to calculate curie temperature with our code.
> I am not in the know of Curie temperature
>
>> we are calculating the elastic constants at ambient condition for the
>> above mentioned ferromagnetic materials....and still i have the doubt of
>> using the structure file of magnetic or non-magnetic to do so?....
>
> Making a calculational model that correctly simulate concrete samples
> and their experimental data is the most important thing, it cannot be
> done without knowing all tiny details of the task, and it takes,
> imho, 80 % of time to work out it. After this, one can quickly
> calculate properties, this is a routine work.
> So, nobody can answer you. We can only give you some small hints, for
> example:
>> On Tue, Aug 18, 2015 at 1:32 PM, Fecher, Gerhard <fecher at uni-mainz.de wrote:
>> Depends, do you like to calculate for above or below the Curie temperature ?
>
> Best wishes
>   Lyudmila Dobysheva
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> 426001 Izhevsk, ul.Kirova 132I am not in the know of Curie temperature
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