Regensburg 2019 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 53: Frustrated Magnets - Strong Spin-Orbit Coupling (joint session TT/MA)

TT 53.2: Vortrag

Donnerstag, 4. April 2019, 09:45–10:00, Theater

Fingerprints of Kitaev physics in RIXS on Na₂IrO₃ and α-Li₂IrO₃ — •Alessandro Revelli¹, Marco Moretti Sala², Giulio Monaco³, Maria Hermanns⁴, Petra Becker⁵, Ladislav Bohatý⁵, Friedrich Freund⁶, Anton Jesche⁶, Philipp Gegenwart⁶, Paul van Loosdrecht¹, Jeroen van den Brink⁷, and Markus Grüninger¹ — ¹II. Physikalisches Institut, Universität zu Köln, Germany — ²ESRF, Grenoble, France — ³Universitá di Trento, Italy — ⁴Stockholm University, Sweden — ⁵Abt. Kristallographie, Institut fur Geologie und Mineralogie, Universität zu Köln, Germany — ⁶Experimentalphysik VI, Universität Augsburg, Germany — ⁷IFW Dresden, Germany

The honeycomb iridates Na₂IrO₃ and α-Li₂IrO₃ are discussed as candidate materials for hosting Kitaev physics. We study the magnetic excitations in these compounds by resonant inelastic x-ray scattering (RIXS) at the Ir L₃ edge, searching for experimental fingerprints of Kitaev physics. In both compounds, we find a broad continuum of excitations centered at q=0. This continuum survives up to 300 K, roughly 20 times the magnetic ordering temperature. The dynamical structure factor shows that spin-spin correlations are restricted to nearest neighbors, a characteristic property of the Kitaev model. Also the polarisation dependence agrees with an interpretation in terms of bond-directional Kitaev exchange interactions.