Berlin 2015 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 30: Correlated Electrons: Spin Systems and Itinerant Magnets – Frustrated Magnets 3 (jointly with MA)

TT 30.14: Talk

Tuesday, March 17, 2015, 13:00–13:15, H 0110

Resonant inelastic x-ray scattering of magnetic excitations in the novel 5d⁴ iridate Ba₂YIrO₆ — •Maximilian Kusch^1,2, T. Dey¹, A. Maljuk¹, S. Wurmehl¹, B. Büchner^1,2, V. M. Katakuri³, B. H. Kim³, D. V. Efremov³, J. van den Brink³, M. Moretti⁴, M. Krisch⁴, and J. Geck¹ — ¹Institute for Solid State and Materials Research, IFW Dresden, Helmholtzstrasse 20, 01069 Dresden, Germany — ²Institut für Festkörperphysik, Technische Universität D-01062 Dresden, Germany — ³Institute for Theoretical Solid State State Physics, IFW Dresden, Germany — ⁴ESRF, B.P.220, 38043 Grenoble, France

In contrast to the much studied 5d⁵ iridates with a spin-orbit coupled J=1/2 ground state, Ba₂YIrO₆ is a realization of a Ir-5d⁴ system. For this case, a ground state J=0 is expected, i.e, Ba₂YIrO₆ should be non-magnetic. Surprisingly, our measurements of the magnetic susceptibility reveal sizable magnetic moments whose microscopic origin is still unclear. Theoretical studies indicate the important role of low-lying magnetic excitations, thereby providing a possible explanation for the unexpected magnetic susceptibility [Khaliullin Phys. Rev. Lett. 111 (2013)]. In addition, our theoretical models predict a considerable dispersion of the J=1 and J=2 excitations in Ba₂YIrO₆. To elucidate the unconventional magnetism of Ba₂YIrO₆ and to determine the dispersions of the J=1 and J=2 excitations experimentally, we performed RIXS studies of this novel 5d⁴ compound. Here we present the results, focusing on the magnetic dispersions in a large region of q-space in comparison to our model calculations.