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A2MCu3F12 : an S = ½ kagome lattice containing material with composition dependent phase transitions

Mercredi 5 mars 2014 15:00 - Duree : 1 heure
Lieu : Room 500-501, Central Building, ESRF - 6 Rue Jules Horowitz - Grenoble

Orateur : Lewis DOWNIE (he University of St. Andrews, Scotland)

A number of members of the family of compounds A2MCu3F12 have been synthesised as potentially highly magnetically frustrated materials.1,2 These have focussed on materials where A is a larger alkali metal ion (i.e. Rb+ and Cs+) and M is a tetravalent metal ion (i.e. Zr4+, Sn4+, and Hf4+). This has shown however, that these materials typically undergo a structural transition to avoid retaining a perfect kagome lattice at reduced temperature. These distortions lead to perfect magnetic frustration being lost and, with further lowering temperature, the onset of magnetic ordering. All is not as it seems, however. For the A = Cs+ case, even analysis of the magnetic properties as a function of temperature suggests that there are at least two different types of structural transitions occurring ; for the M = Zr4+ compound this was found to be due to a change in Zr4+ coordination from 6 to 7 coordinate.3 When A = Rb+ and M = Sn4+ another interesting case is found and this time a perfect kagome lattice is not present at room temperature, nor below. This leads to an unusual magnetic state known as a valence bond solid.2 In this seminar, the further structural analysis of a number of compounds in this family will be discussed, focussing on the solid solutions of Cs2SnCu3F12 and Rb2SnCu3F12 and the novel compounds with M = Ti4+. T. Ono, K. Morita, M. Yano, H. Tanaka, K. Fujii, H, Uekusa, Y. Narumi, K. Kindo, Phys. Rev. B., 2009, 79, 174407. K. Matan, T. Ono, Y. Fukumoto, T. J. Sato, J. Yamamura, M. Yano, K. Morita, H, Tanaka, Nature Phys., 2010, 6, 865. S. A. Reisinger, C. C. Tang, S. P. Thompson, F. D. Morrison, P. Lightfoot, Chem. Mater., 2011, 23, 4234.

Contact : isabelle.combe@esrf.fr

Discipline évènement : (Physique)
Entité organisatrice : (ESRF)
Nature évènement : (Séminaire)
Evènement répétitif : (Séminaire ESRF)
Site de l'évènement : Polygone scientifique

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