Browsing by Author "Khalyavin, Dmitry D."

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    Magnetic Diagram of the High-Pressure Stabilized Multiferroic Perovskites of the BiFe1-yScyO3 Series
    (MDPI, 2020) Fertman, Elena L.; Fedorchenko, Alexey V.; Čižmár, Erik; Vorobiov, Serhii; Feher, Alexander; Radyush, Yury V.; Pushkarev, Anatoli V.; Olekhnovich, Nikolai M.; Stanulis, Andrius; Barron, Andrew R.; Khalyavin, Dmitry D.; Salak, Andrei N.
    Magnetic properties of the high-pressure stabilized perovskite BiFe1-yScyO3 phases (0.1 ≤ y ≤ 0.9) have been studied by means of magnetization measurements and neutron diffraction. The metastable perovskites of this series undergo irreversible polymorphic transformations upon annealing, the phenomenon referred to as conversion polymorphism. It has been found that the solid solutions with y ≥ 0.70 exhibit no long-range magnetic ordering regardless of their polymorph modification, while those with y ≤ 0.60 are all antiferromagnets. Depending on the scandium content, temperature and structural distortions, three types of the antiferromagnetic orderings, involving collinear, canted and cycloidal spin arrangements, have been revealed in the phases obtained via conversion polymorphism and the corresponding magnetic phase diagram has been suggested.
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    Spontaneous reversal of spin chirality and competing phases in the topological magnet EuAl4
    (Springer Nature, 2024) Vibhakar, Anuradha M.; Khalyavin, Dmitry D.; Orlandi, Fabio; Moya, Jamie M.; Lei, Shiming; Morosan, Emilia; Bombardi, Alessandro
    Materials exhibiting a spontaneous reversal of spin chirality have the potential to drive the widespread adoption of chiral magnets in spintronic devices. Unlike the majority of chiral magnets that require the application of an external field to reverse the spin chirality, we observe the spin chirality to spontaneously reverse in the topological magnet EuAl4. Using resonant elastic x-ray scattering we demonstrate that all four magnetic phases in EuAl4 are single-k, where the first two magnetic phases are characterized by spin density wave order and the last two by helical spin order. A single spin chirality was stabilised across the 1mm2 sample, and the reversal of spin chirality occurred whilst maintaining a helical magnetic structure. At the onset of the helical magnetism, the crystal symmetry lowers to a chiral monoclinic space group, explaining the asymmetry in the chiral spin order, and establishing a mechanism by which the spin chirality could reverse via magnetostructural coupling.