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End date: 2022 × Start date: 2020 × Subject: Raman spectroscopy × WGL Institute: IFWD ×

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    Kitaev magnetism and fractionalized excitations in double perovskite Sm2ZnIrO6
    (College Park, ML : American Physical Society, 2020) Singh, Birender; Vogl, M.; Wurmehl, S.; Aswartham, S.; Büchner, B.; Kumar, Pradeep
    The quest for Kitaev spin liquids in particular three-dimensional solids is a long sought goal in condensed matter physics, as these states may give rise to exotic new types of quasiparticle excitations carrying fractional quantum numbers, namely Majorana fermionic excitations. Here we report the experimental signature of this characteristic feature of the Kitaev spin liquid via Raman measurements. Sm2ZnIrO6 is a strongly spin-orbit-coupled Mott insulator where Jeff=1/2 controls the physics, which provides striking evidence for this characteristic feature of the Kitaev spin liquid. As the temperature is lowered, we find that the spin excitations form a continuum in contrast to the conventional sharp modes expected in ordered antiferromagnets. Our observation of a broad magnetic continuum and anomalous renormalization of the phonon self-energy parameters shows the existence of fractionalization excitations in the double-perovskite structure, as theoretically conjectured in a Kitaev-Heisenberg geometrically frustrated double-perovskite system.
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    The boson peak and the first sharp diffraction peak in (As2S3)x(GeS2)1–x glasses
    (Kyiv : Inst. of Semiconductor Physics, 2021) Stronski, A.V.; Kavetskyy, T.S.; Revutska, L.O.; Kaban, I.; Jóvári, P.; Shportko, K.V.; Sergienko, V.P.; Popovych, M.V.
    The parameters of the boson peak (BP) and the first sharp diffraction peak (FSDP) in (As2S3)x(GeS2)1x glasses measured using high-resolution Raman spectroscopy and high-energy synchrotron X-ray diffraction measurements are examined as a function of x. It has been found that there is no correlation between the positions of BP and FSDP. The BP position shows a nonlinear composition behavior with a maximum at about x = 0.4, whereas the FSDP position changes virtually linearly with x. The intensities of both BP and FSDP show nonlinear composition dependences with the slope changes at x = 0.4, although there is no direct proportionality. Analysis of the partial structure factors for the glasses with x = 0.2, 0.4 and 0.6 obtained in another study has shown that the cation-cation atomic pairs of Ge–Ge, Ge–As and As–As make the largest contribution to FSDP, where the Ge–Ge and Ge–As pairs are dominant.