Optical study of the metal-insulator transition in CuIr${}_2$S${}_4$ crystals

Abstract

We present measurements of the optical spectra on single crystals of spinel-type compound \cis. This material undergoes a sharp metal-insulator transition at 230 K. Upon entering the insulating state, the optical conductivity shows an abrupt spectral weight transfer and an optical excitation gap opens. In the metallic phase, Drude components in low frequencies and an interband transition peak at $\sim 2eV$ are observed. In the insulating phase, a new peak emerges around $0.5eV$. This peak is attributed to the transition of electrons from the occupied Ir${}^{3+}$ $t_{2g}$ state to upper Ir${}^{4+}$ $t_{2g}$ subband resulting from the dimerization of Ir${}^{4+}$ ions in association with the simultaneous formations of Ir${}^{3+}$ and Ir${}^{4+}$ octamers as recently revealed by the x-ray diffraction experiment. Our experiments indicate that the band structure is reconstructed in the insulating phase due to the sudden structural transition.

arXiv comment4 pages, 4 figures, to be published in Phys. Rev. B

References in corpus (3)

• New aspects of Verway transition in magnetite
• X-ray-induced disordering of the dimerization pattern and apparent low-temperature enhancement of lattice symmetry in spinel CuIr${}_2$S${}_4$
• X-ray-induced electrical conduction in the insulating phase of thiospinel CuIr2S4

Cited by in corpus (7)

• Optical study of MgTi${}_2$O${}_4$: Evidence for an orbital-Peierls state
• In-gap state and effect of light illumination in CuIr${}_2$S${}_4$ probed by photoemission spectroscopy
• X-ray induced electronic structure change in CuIr${}_2$S${}_4$
• Spin-orbit coupling in octamers in a spinel sulfide CuIr${}_2$S${}_4$: Competition between spin-singlet and quadrupolar states, and its relevance to remnant paramagnetism
• First-order kinetics bottleneck during photoinduced ultrafast insulator-metal transition in 3D orbitally-driven Peierls insulator CuIr${}_2$S${}_4$
• Orbitally-driven insulator-metal transition in CuIr${}_2$S${}_4$: Temperature dependent transient reflectivity study
• Frustrated Kondo chains and glassy magnetic phases on the pyrochlore lattice