Spring Meeting 2016 in Regensburg

Deutsche Physikalische Gesellschaft e. V. (DPG), 31.3.-4.4.2016

Di, 11:00 TT 24.6

Low energy electronic scattering processes in the topological Weyl semimetal TaAs — •Silvia Müllner, Peter Lemmens, Vladimir Gnezdilov, Raman Sankar, and Fangcheng Chou

The topological Weyl semimetal TaAs shows Weyl points as well as topological surface states (Fermi arcs) intimately related to symmetry and strong spin orbit interaction. We find evidence for a low energy maximum in the scattering intensity that is compatible with electronic correlations in a collision dominated regime. We compare our observations with topological insulators.

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Mi, 09:30 TT 42.1

Interplay of Spin and Lattice in a Pseudo-Kagome System — Vladimir Gnezdilov, •Peter Lemmens, Yurii Pashkevich, Alexander Vasiliev, and Peter Berdonosov

The layered cuprates, francisites Cu3Bi(SeO3)2O2X, with X=Br or Cl, with pseudo-kagome structure were studied across the structural and magnetic phase transitions using Raman spectroscopy. For X=Cl a soft optical mode is revealed. The temperature-dependent changes in the phononic and magnetic subsystems of these highly frustrated magnets allow proposing a microscopic magnetic model including Dzyaloshinsky-Moriya interaction to explain the nature of the observed spin-wave excitations.

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Mi, 15:00 TT 59.13

Raman spectroscopic signature of fractionalized excitations in β-Li2IrO3 — •A. Glamazda, S.-H. Do, K.-Y. Choi, and P. Lemmens

The Kitaev honeycomb spin model is known to host exotic fractionalized quasiparticles. Using polarization resolved Raman spectroscopy we study the hyper-honeycomb compound β-Li2IrO3, a promising candidate of a three-dimensional Heisenberg-Kitaev system. A dynamical Raman response exhibits a broad scattering continuum with distinct polarization, which evolves into a quasielastic response with increasing temperature. The given experimental results give a signature of two-particle Majorana spinon excitations and demonstrate that β-Li2IrO3 is close in realizing a three-dimensional Kitaev spin liquid.

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Do, 17:15 TT 73.8

Temperature induced crossover in the collision-dominated Dirac semimetal Cd3As2 — Azat Sharafeev, Vladimir Gnezdilov, •Peter Lemmens, Raman Sankar, and Fangcheng Chou

The 3D topological Dirac semimetal Cd3As2 was studied in a wide range of temperatures and excitation energies using Raman spectroscopy. The temperature evolution of the phononic and the quasielastic electronic scattering is discussed in terms of a collision-dominated regime with pronounced electronic energy density fluctuations. A crossover is observed in the intensity of the signals attributed to a collision-dominated phonon regime.