I3+-Ir4+ Charge Disproportionation of Spinel CuIr2S4 investigated by Synchrotron Radiaton Photoemission

ORAL

Abstract

We have studied the electronic structure of the spinel CuIr$_2 $S$_4$ using synchrotron-radiation photoemission spectroscopy. The phase transition from a high temperature paramagnetic metal to a low temperature diamagnetic insulator at $\sim$230 K is clearly observed through the significant line shape change of the Ir 4$f$ photoemission spectra and the $\sim$0.09 eV gap opening of the valence band spectra. The photon energy dependence of the Ir 4$f$ photoemission spectra enable us to characterize the satellite peaks in the metallic phase of CuIr$_2$S$_4$, providing compelling experimental evidence for the Ir$^{3+}$-Ir$^{4+}$ charge disproportionation in CuIr$_2$S$_4$.

–

Authors

  • Han-Jin Noh

    • Dep. of Phys., Chonnam National University

  • E.-J. Cho

    • Dep. of Phys., Chonnam National University

  • H.-D. Kim

    • Pohang Accelerator Laboratory, POSTECH

  • J.-Y. Kim

    • Pohang Accelerator Laboratory, POSTECH

  • C.-H. Min

    • School of Phys. and Astron., Seoul National University

  • B.-G. Park

    • Dep. of Phys. POSTECH

  • S.-W. Cheong

    • Rutgers Center for Emergent Materials, Rutgers University