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TT: Fachverband Tiefe Temperaturen

TT 72: Poster Session: Correlated Electrons

TT 72.25: Poster

Mittwoch, 14. März 2018, 15:00–19:00, Poster B

RIXS on 5d5 Ba3CeIr2O9 and Ba3TixIr3−xO9 — •Alessandro Revelli1, Marco Moretti Sala2, Giulio Monaco3, Petra Becker4, Ladislav Bohatý4, Thomas Koethe1, Tobias Fröhlich1, Maria Hermanns5, Paul H.M. van Loosdrecht1, Jeroen van den Brink6, and Markus Grüninger11II. Physikalisches Institut, Universität zu Köln — 2ESRF, Grenoble — 3Dipart. di Fisica, Universita di Trento — 4Abt. Kristallographie, Institut für Geologie & Mineralogie, Universität zu Köln — 5Institut für Theoretische Physik, Universität zu Köln — 6IFW, Dresden

Spin-orbit entangled j = 1/2 Mott insulators set the stage for fascinating novel quantum states of matter. In corner-sharing geometry of the IrO6 octahedra, one finds strong Heisenberg exchange between j = 1/2 moments, while edge-sharing geometry features bond-directional Kitaev exchange. However, the case of face-sharing octahedra has hardly been explored. Using resonant inelastic x-ray scattering (RIXS), we study the 5d5 compound Ba3CeIr2O9 with face-sharing octahedra forming triangular layers. Both hopping and spin-orbit coupling are large. The RIXS data reveal the first and exceptionally clean realization of the quasi-molecular-orbital scenario that was debated extensively (but refuted) for Na2IrO3. The ground state shows a total j = 0 singlet predominantly built from j = 1/2 moments with the corresponding triplet excitation lying at an extraordinarily large energy. For M=Ti, the compound Ba3TixIr3−xO9 exists for different values of x and shows Ti/Ir site disorder. In RIXS we observe a coexistence of j = 1/2 moments and quasi-molecular singlets.

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DPG-Physik > DPG-Verhandlungen > 2018 > Berlin