Researchers from the Max Planck Institute for Solid State Research in Stuttgart have measured the complex dielectric function of Na3Ir3O8 single crystals by spectroscopic ellipsometry in the far-infrared at ANKA-IR1. The experiments provide insights into electron-phonon interactions in transition metal oxides.
The complex dielectric function of high-quality Na3Ir3O8 single crystals determined by spectroscopic ellipsometry in the spectral range from 15 meV to 2 eV is reported.
The far-infrared phonon spectra exhibit highly asymmetric line shapes characteristic of Fano resonances. With decreasing temperature, a sharp increase of the infrared intensity of the Fano-shaped phonon modes was observed accompanied by concomitant changes in the low-energy electronic background, formed by electronic transitions between Ir 5d t2g bands of a mostly Jeff = 1/2 character. The role of the complex hyperkagome lattice structure and strong spin-orbit coupling is considered.
D. Pröpper, A. N. Yaresko, T. I. Larkin, T. N. Stanislavchuk, A. A. Sirenko, T. Takayama, A. Matsumoto, H. Takagi, B. Keimer, and A. V. Boris: Fano Resonances in the Infrared Spectra of Phonons in Hyperkagome Na3Ir3O8, Phys. Rev. Lett. 112, 087401 – Published 26 February 2014