This discussion may be very misleading. The concept of frustation is very popular, but whatever geometrical frustation may exist in a fcc lattice, the magnetic structure of NiO is perfectly collinear (see for instance in the MAGNDATA database of the Bilbao crystallographic server: http://webbdcrista1.ehu.es/magndata/index.php?this_label=1.6 <http://webbdcrista1.ehu.es/magndata/index.php?this_label=1.6>) , and each triangular plane of spins perpendicular to the <1,1,1> has NO frustration, as the couplings within the planes are FM . Therefore the small structural structural strain can not be caused to get rid of the frustration.
In general, any magnetic ordering breaks the symmetry of the system, and structural distortions compatible with the new symmetry can happen due to magneto-structural coupling. Often this coupling is too weak to be detected, but in other cases like NiO is strong enough. In the case of NiO the magnetic order reduces the symmetry to monoclinic, and the observed structural distortion corresponds to this symmetry break. best regards, Manuel > El 10/6/2016, a las 0:46, delamora <[email protected]> escribió: > > No, because in NaCl you do not have magnetic moments that want to find order, > so there is no frustration > In NiO the distortion is a way out of this frustration > De: Wien <[email protected] > <mailto:[email protected]>> en nombre de Abderrahmane > Reggad <[email protected] <mailto:[email protected]>> > Enviado: jueves, 9 de junio de 2016 05:26:15 p. m. > Para: [email protected] <mailto:[email protected]> > Asunto: Re: [Wien] Why the antiferromagnetic structure of Cr is still cubic > > Thanks Dr Delamora for your reply > > Now I inderstand that and according to this raison "geometrical frustration" > , is there any structural distortion in the planes > (100) and (110) for the NaCl structure. > > Best regards > -- > Mr: A.Reggad > Laboratoire de Génie Physique > Université Ibn Khaldoun - Tiaret > Algerie > > > _______________________________________________ > Wien mailing list > [email protected] <mailto:[email protected]> > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien > <http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien> > SEARCH the MAILING-LIST at: > http://www.mail-archive.com/[email protected]/index.html > <http://www.mail-archive.com/[email protected]/index.html> ************************************************** J. Manuel Perez-Mato Fac. Ciencia y Tecnologia, Universidad del Pais Vasco, UPV 48080 BILBAO, Spain tel. +34 946012473 fax. +34 946013500 ***************************************************
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