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End date: 2023 × Start date: 2023 × Start date: 2015 × Publisher: Bristol : IOP Publ. × WGL Institute: IFWD ×

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Now showing 1 - 3 of 3
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    Impact of Mn-Pn intermixing on magnetic properties of an intrinsic magnetic topological insulator: the µSR perspective
    (Bristol : IOP Publ., 2023) Sahoo, M.; Salman, Z.; Allodi, G.; Isaeva, A.; Folkers, L.; Wolter, A.U.B.; Büchner, B.; De Renzi, R.
    We investigated the magnetic properties of polycrystalline samples of the intrinsic magnetic topological insulators MnPn2Te4, with pnictogen Pn = Sb, Bi, by bulk magnetization and μSR. DC susceptibility detects the onset of magnetic ordering at TN = 27 K and 24 K and a field dependence of the macroscopic magnetization compatible with ferri- (or ferro-) and atiferro- magnetic ordering, respectively. Weak transverse field (wTF) Muon Spin Rotation (μSR) confirms the homogeneous bulk nature of magnetic ordering at the same two distinct transition temperatures. Zero Field (ZF) μSR shows that the Sb based material displays a broader distribution of internal field at the muon, in accordance with a larger deviation from the stoichiomectric composition and a higher degree of positional disorder (Mn at the Pn(6c) site), which however does not affect significantly the sharpness of the thermodynamic transition, as detected by the muon magnetic volume fraction and the observability of a critical divergence in the longitudinal and transverse muon relaxation rates.
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    Recovery of release cloud from laser shock-loaded graphite and hydrocarbon targets: in search of diamonds
    (Bristol : IOP Publ., 2022) Schuster, A.K.; Voigt, K.; Klemmed, B.; Hartley, N.J.; Lütgert, J.; Zhang, M.; Bähtz, C.; Benad, A.; Brabetz, C.; Cowan, T.; Döppner, T.; Erb, D.J.; Eychmüller, A.; Facsko, S.; Falcone, R.W.; Fletcher, L.B.; Frydrych, S.; Ganzenmüller, G.C.; Gericke, D.O.; Glenzer, S.H.; Grenzer, J.; Helbig, U.; Hiermaier, S.; Hübner, R.; Laso Garcia, A.; Lee, H.J.; MacDonald, M.J.; McBride, E.E.; Neumayer, P.; Pak, A.; Pelka, A.; Prencipe, I.; Prosvetov, A.; Rack, A.; Ravasio, A.; Redmer, R.; Reemts, D.; Rödel, M.; Schoelmerich, M.; Schumacher, D.; Tomut, M.; Turner, S.J.; Saunders, A.M.; Sun, P.; Vorberger, J.; Zettl, A.; Kraus, D.
    This work presents first insights into the dynamics of free-surface release clouds from dynamically compressed polystyrene and pyrolytic graphite at pressures up to 200 GPa, where they transform into diamond or lonsdaleite, respectively. These ejecta clouds are released into either vacuum or various types of catcher systems, and are monitored with high-speed recordings (frame rates up to 10 MHz). Molecular dynamics simulations are used to give insights to the rate of diamond preservation throughout the free expansion and the catcher impact process, highlighting the challenges of diamond retrieval. Raman spectroscopy data show graphitic signatures on a catcher plate confirming that the shock-compressed PS is transformed. First electron microscopy analyses of solid catcher plates yield an outstanding number of different spherical-like objects in the size range between ten(s) up to hundreds of nanometres, which are one type of two potential diamond candidates identified. The origin of some objects can unambiguously be assigned, while the history of others remains speculative.
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    Circular stripe domains and cone state vortices in disk-shaped exchange coupled magnetic heterostructures
    (Bristol : IOP Publ., 2022) Zaiets, Oleksandr; Kravchuk, Volodymyr P.; Pylypovskyi, Oleksandr V.; Makarov, Denys; Sheka, Denis D.
    Vertically stacked exchange coupled magnetic heterostructures of cylindrical geometry can host complex noncolinear magnetization patterns. By tuning the interlayer exchange coupling between a layer accommodating magnetic vortex state and an out-of-plane magnetized layer, one can efficiently realize new topological chiral textures such as cone state vortices and circular stripe domains. We study how the number of circular stripes can be controlled by both the interlayer exchange coupling and the sample geometrical parameters. By varying geometrical parameters, a continuous phase transition between the homogeneous state, cone state vortex, circular stripe domains, and the imprinted vortex takes place, which is analysed by full scale micromagnetic simulations. The analytical description provides an intuitive pictures of the magnetization textures in each of these phases. The possibility to realize switching between different states allows for engineering magnetic textures with possible applications in spintronic devices.