Browsing by Author "Sushkov, OP"

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    Increase of the stability range of the skyrmion phase in doped Cu2OSeO3
    (Australian Institute of Physics, 2020-02-04) Sauceda Flores, JA; Rov, R; Camacho, L; Spasovski, M; Vella, J; Yick, S; Gilbert, EP; Han, MG; Zhu, Y; Seidel, J; Kharkov, Y; Sushkov, OP; Söhnel, T; Ulrich, C
    A skyrmion is a topological stable particle-like object comparable to a spin vortex at the nanometre scale. It consists of an about 50 nm large spin rotation and its spin winding number is quantized. Once formed, the skyrmions order in a two dimensional, typically hexagonal superstructure perpendicular to an applied external magnetic field (see Fig. 1). Its dynamics has links to flux line vortices as in high temperature superconductors. Cu2OSeO3 is a unique case of a multiferroic materials where the skyrmion dynamics could be controlled through the application of an external electric field. The direct control of the skyrmion dynamics through a non-dissipative method would offer technological benefits and unique possibilities for testing fundamental theories also related to the Higgs Boson whose theoretical description has similarities to skyrmions. Important for technological applications is a stability range of the skyrmion phase up to room temperature. While room temperature skyrmion materials exist, Cu2OSeO3 orders magnetically below 58 K. Our combined small angle neutron scattering (see Fig. 2), SQUID magnetization measurements and electron microscopy investigations did provide direct evidence that the stability range of the skyrmion phase can be extended in Te-doped Cu2OSeO3. The understanding of this effect will help to obtain deeper insights in the magnetic correlations in charge of the skyrmion formation and will thus help to systematically search for skyrmion materials with phase transition temperatures towards room temperature.
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    Phonon mode softening at the ferroelectric transition in Eu0.5Ba0.5TiO3
    (Springer Nature, 2010-11-10) Rowan-Weetaluktuk, WN; Ryan, DH; Sushkov, AO; Eckel, S; Lamoreaux, SK; Sushkov, OP; Cadogan, JM; Yethiraj, M; Studer, AJ
    We have observed the effects of phonon mode softening at the ferroelectric transition in Eu0.5Ba0.5TiO3 by 151Eu Mössbauer spectroscopy. Both Eu2+ and Eu3+ spectral components are observed in the relative area ratio of 90% : 10% and both show a decrease in subspectral area at the transition, centred at 175 K, due to phonon mode softening. Surprisingly, the temperature dependence of the f-factor shows a much stronger response in the Eu3+ component than in the Eu2+ one. Preliminary analysis of neutron powder diffraction data rules out the possibility that some of the europium might be located on titanium sites. © 2010 Springer Science Business Media B.V.