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<meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">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: <a href="http://webbdcrista1.ehu.es/magndata/index.php?this_label=1.6" class="">http://webbdcrista1.ehu.es/magndata/index.php?this_label=1.6</a>) , 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.<div class=""><br class=""></div><div class="">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.</div><div class=""><br class=""></div><div class="">best regards,</div><div class=""><br class=""></div><div class="">Manuel</div><div class=""><br class=""><div><blockquote type="cite" class=""><div class="">El 10/6/2016, a las 0:46, delamora <<a href="mailto:delamora@unam.mx" class="">delamora@unam.mx</a>> escribió:</div><br class="Apple-interchange-newline"><div class=""><div id="divtagdefaultwrapper" style="font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; font-size: 12pt; background-color: rgb(255, 255, 255); font-family: Calibri, Arial, Helvetica, sans-serif;" class=""><div style="margin-top: 0px; margin-bottom: 0px;" class="">No, because in NaCl you do not have magnetic moments that want to find order, so there is no frustration</div><div style="margin-top: 0px; margin-bottom: 0px;" class="">In NiO the distortion is a way out of this frustration<br class=""></div></div><hr tabindex="-1" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; display: inline-block; width: 1046.625px;" class=""><span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class=""></span><div id="divRplyFwdMsg" dir="ltr" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><font face="Calibri, sans-serif" style="font-size: 11pt;" class=""><b class="">De:</b><span class="Apple-converted-space"> </span>Wien <<a href="mailto:wien-bounces@zeus.theochem.tuwien.ac.at" class="">wien-bounces@zeus.theochem.tuwien.ac.at</a>> en nombre de Abderrahmane Reggad <<a href="mailto:jazairdz@gmail.com" class="">jazairdz@gmail.com</a>><br class=""><b class="">Enviado:</b><span class="Apple-converted-space"> </span>jueves, 9 de junio de 2016 05:26:15 p. m.<br class=""><b class="">Para:</b><span class="Apple-converted-space"> </span><a href="mailto:wien@zeus.theochem.tuwien.ac.at" class="">wien@zeus.theochem.tuwien.ac.at</a><br class=""><b class="">Asunto:</b><span class="Apple-converted-space"> </span>Re: [Wien] Why the antiferromagnetic structure of Cr is still cubic</font><div class=""> </div></div><div style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><div dir="ltr" class="">Thanks Dr Delamora for your reply <div class=""><br class=""></div><div class="">Now I inderstand that and according to this raison <span style="font-family: courier, 'courier new', monospace; font-size: 14px; line-height: 19.6px; white-space: pre-wrap;" class="">"geometrical frustration" , is there any structural distortion in the planes
(100) and (110) for the NaCl structure.</span><div class=""><br class=""></div><div class="">Best regards</div>--<span class="Apple-converted-space"> </span><br class=""><div class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr" class=""><div class=""><div dir="ltr" class=""><div class=""><div dir="ltr" class=""><div class=""><div dir="ltr" class=""><div class=""><div dir="ltr" class=""><div class=""><div dir="ltr" class=""><div class=""><div dir="ltr" class=""><div style="font-family: monospace;" class=""><div class=""><font size="2" class=""><span style="color: rgb(0, 0, 255);" class="">Mr: A.Reggad</span> <span class="Apple-converted-space"> </span><br class=""><span style="background-color: rgb(238, 238, 238);" class=""><span style="color: blue;" class="">Laboratoire de Génie Physique</span></span><br class=""></font></div><font size="2" class=""><span style="color: rgb(0, 0, 255);" class="">Université Ibn Khaldoun - Tiaret</span><br class=""></font></div><div class=""><font size="2" class=""><span style="font-family: monospace;" class=""><span style="color: rgb(0, 0, 255);" class="">Algerie</span></span></font><br class=""></div><div class=""><div class=""><br class=""><span style="font-family: 'times new roman', serif;" class=""><span style="color: blue;" class=""></span></span><br class=""></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div></div><span style="font-family: Helvetica; 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<span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px;"><div class="">**************************************************</div><div class="">J. Manuel Perez-Mato<br class="">Fac. Ciencia y Tecnologia,<br class="">Universidad del Pais Vasco, UPV<br class="">48080 BILBAO,<br class="">Spain<br class=""><br class="">tel. +34 946012473<br class="">fax. +34 946013500<br class="">***************************************************<br class=""></div></span>
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