[Wien] AFM type II

Wed Jan 29 13:16:37 CET 2020

Dear Martin,
this concerns your remark:
"With two magnetic species, say, Mn and Cu, you would wind up with
different size of the moment on Mn and Cu. I know of no case where exact
compensation into an AFM structure occures by accident in such a
situation."

You may have the situation of a completely compensated ferrimagnet exampels are:
CrMnSb (or VFeSb) in the cubic C1b structure
H. van Leuken and R. A. de Groot, Phys. Rev. Lett. 74, 1171 (1995)
or more complicated
Mn1.5FeV0.5Al
Rolf Stinshoff et al; Phys. Rev. B 95, 060410(R) (2017)

However, it is by purpose rather than by accident.

This was already found by Neel in his work on antiferromagnets (probably it is mentioned in the Nobel lecture)

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 [wien-bounces at zeus.theochem.tuwien.ac.at] im Auftrag von pieper [pieper at ifp.tuwien.ac.at]
Gesendet: Mittwoch, 29. Januar 2020 12:49
An: A Mailing list for WIEN2k users
Betreff: Re: [Wien] AFM type II

No one can give you an honest answer without knowing the structure you
put these elements in. Zr, S, Se are almost certainely non-magnetic, but
there are quite a few structures with magnetic moments on Cr, Cu, and of
course on Mn.

To make terminology more complicated, remember that AFM means fully
compensated magnetic moments. The net magnetization of a unit cell of
some AFM structure is zero. This does not happen by coincidence, it is
because by symmetry all moments have the same size, and there are as
many of them pointing in one direction as there are pointing in exactly
the opposite direction.

So, IF your compound REALLY is AFM by experiment (NO net magnetization),
you almost certainely have only one magnetic species in there (probably
Mn). With two magnetic species, say, Mn and Cu, you would wind up with
different size of the moment on Mn and Cu. I know of no case where exact
compensation into an AFM structure occures by accident in such a
situation. You always get something with net moment - and these are
called ferrimagnetic structures. And since we are at it: there are
canted and helical strucutures where the moments are not collinear (not
within the scope of Wien2k), there are spin density waves, ...

Scanning this thread my advice would be to study a (good) book on solid
state physics, with special attention payed to its chapter discussing
magnetic order. If it doesn't have such a chapter its not a good book -
at least not for you. Do NOT use wikipedia or this mailing list and its
archive as a substitute for such a reading. It will not work.

---
Dr. Martin Pieper
Karl-Franzens University
Institute of Physics
Universitätsplatz 5
A-8010 Graz
Austria
Tel.: +43-(0)316-380-8564

Am 2020-01-27 17:45, schrieb djamel slamnia:
> WHEN I STUDY A COMPOUND CONTAINS THIS ELEMENETS CU  MN   CR  ZR S SE
>
> BETWEEN THEM WITCH ONE TO PUT IT SPIN UP OR DOWN AND NON-MAGNETIC ???
>
>  Le lundi 27 janvier 2020 à 14:22:39 UTC+1, Gavin Abo
> <gsabo at crimson.ua.edu> a écrit :
>
>  As previously mentioned [1], a short literature survey showed that
> AFM type II and III are terms used for _fcc_ and _bcc_ lattices.
> Since spacegroup 156 is not one of those, it might be inappropriate to
> use those terms for spacegroup 156 having a _primitive_ lattice [2] of
> the hexagonal crystal family.  If you do a more extensive literature
> survey yourself and find a paper (article, book, etc.) that defines
> the AFM magnetic orders for spacegroup 156, then reference and use it
> for what the AFM order is.  If there is not any notations and terms
> for AFM magnetic orders for spacegroup 156, you might have to make
> your own figure or write in your own words what the definition is
> should any AFM magnetic orders exist for it.
> Keep in mind that as mentioned before in the mailing list archive, the
> initial configuration can be set in case.inst with "instgen_lapw -ask"
> [3].
>
> Though, you need to check the final magnetic order that comes out of
> the scf [4], because the configuration set in case.inst with
> instgen_lapw is just the initial one that could change [5,6].
>
> It is also possible to try to force a magnetic order using dmatup/dn
> matrices but the final magnetic order is still what comes out of the
> scf and could be different [6-11].
>
> Therefore, it likely not beneficial to name the AFM order before
> starting a calculation such that you would likely want to identify the
> name of the magnetic order after having finished the converged
> calculation.
>  [1]
> https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg19515.html
> [2] https://en.wikipedia.org/wiki/Crystal_structure#Lattice_systems
> [3]
> https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg10044.html
>
> [4]
> https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg17516.html
> [5]
> https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg03243.html
> [6]
> https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg06739.html
> [7]
> https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg14259.html
> [8]
> https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg05054.html
> [9]
> https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg13124.html
> [10]
> https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg16281.html
> [11]
> https://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/msg16286.html
>
> On 1/26/2020 1:01 PM, djamel slamnia wrote:
>
>>
>
> THANKS AGAIN SIR
>
> I NEED TO KNOW WHAT IS THE AFM ORDERS FOR P3M1 (156) ??? TYPE II OR
> III
>
> THANKS IN ADVANCE
>
>>
>
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