Berlin 2018 – wissenschaftliches Programm

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 27: Postersession KFM

KFM 27.33: Poster

Donnerstag, 15. März 2018, 15:00–17:00, Poster E

Discovery of a high-pressure RuCl3 phase with complete cation disorder — •Lisa Leißner, Ulrich Bläß, Marcus Schwarz, and Edwin Kroke — Tu Bergakademie Freiberg, Freiberg, Germany

The alpha form of Ruthenium(III)-chloride is a hot topic in spin liquid physics because it is one of the most promising materials to realize the Kitaev model of a quantum spin liquid. It fulfills the criteria for realizing the Kitaev interactions (Jackeli & Khaliullin 2009, Glamazda et al 2017). At low temperatures, it orders to a zigzag magnetic order. However, in Raman spectroscopy as well as inelastic neutron scattering some hints of spin liquid physics could be observed (Sears et al, 2017). The transition temperature is strongly dependent of the sample, especially its stacking faults. The effective magnetic interactions between the Ru-moments strongly depend on the distance and Ru-Cl-Ru angle. Hence, a change of one of these parameters, as e.g. occurring after second order phase transitions, may change the ratio between Kitaev and Heisenberg interactions. In order to explore such potential transitions, we have conducted various heated and unheated high pressure experiments to explore stable or metastable high-pressure phases of RuCl3. Multianvil experiments led to the formation of single crystals of a new RuCl3 phase. Single crystal X-ray diffraction revealed a small unit cell with space for two atom sites only, while spectroscopic measurements indicate that a Ru:Cl ratio of 1:3 is still present. We thus have synthesized a new and possibly metastable hexagonal form of RuCl3 with a completely random occupation of one third of the cation site.