Browsing by Author "Häußler, Ellen"

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    Open Access
    Data Underpinning: Correlated proton disorder in the crystal structure of the double hydroxide perovskite CuSn(OH)₆
    (Technische Universität Dresden, 2025-01-16) Peets, Darren Campbell; Kulbakov, Anton A.; Häußler, Ellen; Parui, Kaushick K.; Mannathanath Chakkingal, Aswathi; Pavlovskii, Nikolai S.; Pomjakushin, Vladimir Yu.; Cañadillas-Delgado, Laura; Hansen, Thomas; Doert, Thomas; Inosov, Dmytro S.
    This contains the data underpinning our paper on CuSn(OH)₆. The abstract of the article is reproduced here: CuSn(OH)6 is a quantum spin system from the family of magnetic double perovskite hydroxides, having a frustrated magnetic sublattice. It is also known as the natural mineral mushistonite, whose crystal structure has remained elusive for decades. Here we employ x-ray and neutron powder diffraction to solve the crystal structure of CuSn(OH)6 and propose a structure model in the orthorhombic space group Pnnn with correlated proton disorder. The occupation of the hydrogen sites in the structure is constrained by “ice rules” similar to those known for water ice. The resulting frustration of the hydrogen bonding network is likely to have a complex and interesting interplay with the strong magnetic frustration expected in the face-centred magnetic sublattice. Structural distortions, which are quite pronounced in Cu2+ compounds due to the Jahn-Teller effect, partially alleviate both types of frustration. We also show that hydrostatic pressure tends to suppress proton disorder through a sequence of proton-ordering transitions, as some of the split hydrogen sites merge already at 1.75 GPa while others show a tendency toward possible merging at higher pressures.
  • Item
    Open Access
    Data Underpinning: Magnetic phase diagram of rouaite, Cu₂⁢(OH)₃⁢NO₃
    (Technische Universität Dresden, 2024-11-04) Peets, Darren Campbell; Mannathanath Chakkingal, Aswathi; Kulbakov, Anton A.; Grumbach, Justus; Pavlovskii, Nikolai S.; Stockert, Ulrike; Parui, Kaushick Krishnakanta; Avdeev, Maxim; Kumar, Ramender; Niwata, Issei; Häußler, Ellen; Gumeniuk, Roman; Stewart, J. Ross; Tellam, James P.; Pomjakushin, Vladimir; Granovsky, Sergey; Doerr, Mathias; Hassinger, Elena; Zherlitsyn, Sergei; Ihara, Yoshihiko; Inosov, Dmytro S.
    This contains the data underpinning our recent paper on rouaite, Cu₂⁢(OH)₃⁢NO₃, published in Phys. Rev. B 110, 054442 (2024). The abstract of the article is reproduced below: Spinon-magnon mixing was recently reported in botallackite Cu2⁢(OH)3⁢Br with a uniaxially compressed triangular lattice of Cu2+ quantum spins [H. Zhang et al., Phys. Rev. Lett. 125, 037204 (2020)]. Its nitrate counterpart rouaite, Cu2⁢(OH)3⁢NO3, has a highly analogous structure and might be expected to exhibit similar physics. To lay a foundation for research on this material, we clarify rouaite's magnetic phase diagram and identify both low-field phases. The low-temperature magnetic state consists of alternating ferromagnetic and antiferromagnetic chains, as in botallackite, but with additional canting, leading to net moments on all chains which rotate from one chain to another to form a 90∘ cycloidal pattern. The higher-temperature phase is a helical modulation of this order, wherein the spins rotate from one Cu plane to the next. This extends to zero temperature for fields perpendicular to the chains, leading to a set of low-temperature field-induced phase transitions. Rouaite may offer another platform for spinon-magnon mixing, while our results suggest a delicate balance of interactions and high tunability of the magnetism.