Browsing by Author "Granovsky, Sergey"

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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.
Open Access
Data Underpinning: Disorder-driven magnetic duality in the spin-½ system ktenasite, Cu₂.₇Zn₂.₃(SO₄)₂(OH)₆·6H₂O
(Technische Universität Dresden, 2025-10-17) Parui, Kaushick K.; Kulbakov, Anton A.; Gumeniuk, Roman; Carrillo-Aravena, Eduardo; Fernández-Díaz, María Teresa; Savvin, Stanislav; Korshunov, Artem; Granovsky, Sergey; Doert, Thomas; Inosov, Dmytro S.; Peets, Darren C.
Article abstract: Disorder in frustrated quantum systems can critically influence their magnetic ground states and drive exotic magnetic behavior. In the S = ½ system ktenasite, Cu₂.₇Zn₂.₃(SO₄)₂(OH)₆·6H₂O, we show that structural disorder drives an unexpected dimensional crossover and stabilizes a rare coexistence of distinct magnetic states. Neutron diffraction reveals significant Cu/Zn mixing at the Cu2 site, which tunes the Cu²⁺ sublattice from a two-dimensional scalene-distorted triangular lattice into a one-dimensional spin-chain network. Magnetic susceptibility, neutron diffraction, ac susceptibility, and specific heat measurements collectively indicate magnetic duality: a coexistence of incommensurate long-range magnetic order below TN = 4 K and a cluster spin-glass state with Tf = 3.28 K at f = 10 Hz. Our findings highlight ktenasite as a rare platform where structural disorder tunes the effective dimensionality and stabilizes coexisting ordered and glassy magnetic phases, offering a unique opportunity to explore the interplay of frustration, disorder, and dimensional crossover in quantum magnets.
Open Access
Data Underpinning: Disordered ground state in the 3D face-centred frustrated spin-5/2 system MnSn(OH)₆
(Technische Universität Dresden, 2025-03-04) Parui, Kaushick K.; Kulbakov, Anton A.; Häußler, Ellen; Pavlovskii, Nikolai S.; Mannathanath Chakkingal, Aswathi; Avdeev, Maxim; Gumeniuk, Roman; Granovsky, Sergey; Mistonov, Alexander; Zvyagin, Sergei; Doert, Thomas; Inosov, Dmytro S.; Peets, Darren C.
This contains the data underpinning our paper on MnSn(OH)₆. The abstract of the article is reproduced below: Frustrated magnetism in face-centered cubic (fcc) magnetic sublattices remains underexplored but holds considerable potential for exotic magnetic behavior. Here, we report on the crystal structural, magnetic and thermodynamic properties of the A-site-vacant double hydroxide perovskite MnSn(OH)₆. Despite dominant antiferromagnetic interactions among Mn²⁺ moments, evidenced by a negative Curie-Weiss temperature, the lack of a sharp thermodynamic transition down to 350 mK implies the absence of long-range magnetic order. However, a broad hump at 1.6 K suggests short-range correlations and spin freezing, with power-law behavior consistent with a spin-glass state. Neutron diffraction at low temperatures confirms the presence of three-dimensional (3D) antiferromagnetic correlations, manifesting as diffuse magnetic scattering with a correlation length ξ = 24.66 Å and a magnetic propagation vector k = (0 0 ½) at 20 mK.
Open Access
Data Underpinning: Stacking Disorder in Novel ABAC-Stacked Brochantite, Cu₄SO₄(OH)₆
(Technische Universität Dresden, 2025-01-16) Mannathanath Chakkingal, Aswathi; Fuller, Chloe; Avdeev, Maxim; Gumeniuk, Roman; Parui, Kaushick K.; Rahn, Marein C.; Pabst, Falk; Wang, Yiran; Granovsky, Sergey; Korshunov, Artem; Chernyshov, Dmitry; Inosov, Dmytro S.; Peets, Darren C.
Abstract of the accompanying article: In geometrically frustrated magnetic systems, weak interactions or slight changes to the structure can tip the delicate balance of exchange interactions, sending the system into a different ground state. Brochantite, Cu₄SO₄(OH)₆, has a copper sublattice composed of distorted triangles, making it a likely host for frustrated magnetism, but exhibits stacking disorder. The lack of synthetic single crystals has limited research on the magnetism in brochantite to powders and natural mineral crystals. We grew crystals which we find to be a new polytype with a tendency toward ABAC stacking and some anion disorder, alongside the expected stacking disorder. Comparison to previous results on natural mineral specimens suggests that cation disorder is more deleterious to the magnetism than anion and stacking disorder. Our specific heat data suggest a double transition on cooling into the magnetically ordered state.