Dresden 2017 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 42: Correlated Electrons: Frustrated Magnets - Strong Spin-Orbit Coupling 2

TT 42.10: Talk

Wednesday, March 22, 2017, 12:00–12:15, HSZ 304

Raman Spectroscopy on the putative Kitaev Material RuCl₃ — •Thomas Koethe¹, Sebastian Kaul¹, Raphael German¹, Petra Becker², Markus Grüninger¹, and Paul van Loosdrecht¹ — ¹Institute of Physics 2, University of Cologne — ²Institute for Geology and Mineralogy, University of Cologne

The famous Kitaev model with bond-directional Ising-type interactions on tricoordinated lattices allows for an exotic spin liquid ground state and Majorana fermion excitations. Real materials like the spin-orbit driven Mott insulator RuCl₃ usually show an additional isotropic Heisenberg interaction competing with the Kitaev interactions. Raman spectroscopy is an excellent tool to investigate unconventional states of matter and provides information not only about the electronic ground state of the material, whose j=1/2 nature is a requirement for the Kitaev physics, but also about the nature of the excitations. Though we observe a low energy scattering continuum, our results do not seem to be compatible with current theoretical predictions for the Majorana continuum. We do see, however, a Fano-type phonon continuum coupling which may be compatible with theoretical expectations. Electronic excitations at higher energies challenge the previously proposed electronic structure of the material.