In NiO the Ni makes an FCC structure, you cannot have an antiferromagnetic arrangement in a triangular lattice (for example in 1,1,1 planes), even less in the FCC, which is triangular in many planes, so there is what is called "geometrical frustration"
On the other hand, in Cr you have the "Cr up" and "Cr dn" alternated and you can have a clear antiferromagnetic arrangement Pablo ________________________________ De: Wien <[email protected]> en nombre de Abderrahmane Reggad <[email protected]> Enviado: miércoles, 8 de junio de 2016 05:43 a. m. Para: [email protected] Asunto: [Wien] Why the antiferromagnetic structure of Cr is still cubic Dear wien2k users I have read that the antiferromagnetic ordering is accompanied with a little structural distortion as in the case of NiO. This latter is characterized by a distortion from NaCl to rhomboherdral structure; but for the chromide Cr the structure is still cubic when there is a magnetic transition from paramagnetic to antiferromagnetic state. Best regards -- Mr: A.Reggad Laboratoire de Génie Physique Université Ibn Khaldoun - Tiaret Algerie
_______________________________________________ Wien mailing list [email protected] http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/[email protected]/index.html
