Optical conductivity of the metallic pyrochlore iridate Pr${}_2$Ir${}_2$O${}_7$: Influence of spin-orbit coupling and electronic correlations on the electronic structure

Abstract

The synergy of strong spin-orbit coupling and electron-electron interactions gives rise to unconventional topological states, such as topological Mott insulator, Weyl semimetal, and quantum spin liquid. In this study, we have grown single crystals of the pyrochlore iridate Pr${}_2$Ir${}_2$O${}_7$ and explored its magnetic, lattice dynamical, and electronic properties. While Raman spectroscopy data reveal six phonon modes confirming the cubic \textit{Fd$\bar{3}$m} crystal symmetry, dc magnetic susceptibility data show no anomalies and hence indicate the absence of magnetic phase transitions down to 2~K. Both temperature-dependent electric transport and optical conductivity data reveal the metallic character of Pr${}_2$Ir${}_2$O${}_7$. The optical conductivity spectrum contains a mid-infrared absorption band, which becomes more pronounced with decreasing temperature due to spectral weight transfer from high to low energies. The presence of the mid-infrared band hints at the importance of correlation physics. The optical response furthermore suggests that Pr${}_2$Ir${}_2$O${}_7$ is close to the Weyl semimetal phase.

11 pages, 8 figures, accepted for publication in Phys. Rev. B

References in corpus (15)

• Novel Jeff = 1/2 Mott State Induced by Relativistic Spin-Orbit Coupling in Sr2IrO4
• Electrodynamics of Correlated Electron Materials
• Bandwidth-Controlled Insulator-Metal Transition and Correlated Metallic State in 5$d$ Transition Metal Oxides Sr${}_{n+1}$Ir${}_n$O${}_{3n+1}$ ($n$=1, 2, and $\infty$)
• Use of X-ray scattering functions in Kramers-Kronig analysis of reflectance
• A New Type of Quantum Criticality in the Pyrochlore Iridates
• Low frequency optical conductivity in graphene and in other scale-invariant two-band systems
• Comparative studies of low temperature X-ray diffraction experiments on R2Ir2O7 (R = Nd, Eu, and Pr)
• Evolution of structure, magnetism and electronic transport in doped pyrochlore iridate Y${}_2$Ir${}_{2-x}$Ru${}_x$O${}_7$
• High-pressure versus isoelectronic doping effect on the honeycomb iridate Na${}_2$IrO${}_3$
• Magnetic and transport properties in pyrochlore iridates (Y${}_{1-x}$Pr${}_x$)${}_2$Ir${}_2$O${}_7$: The role of $f$-$d$ exchange interaction and $d$-$p$ orbital hybridization
• Optical signature of the pressure-induced dimerization in the honeycomb iridate $\alpha$-Li${}_2$IrO${}_3$
• Experimental signatures of versatile Weyl semimetal in pyrochlore iridate with spin-ice like magnetic orders
• Magnetic field tuning of the valley population in the Weyl phase of Nd${}_2$Ir${}_2$O${}_7$
• Infrared study of the layered, magnetic insulator Mn(Bi${}_{0.07}$Sb${}_{0.93}$)${}_2$Te${}_4$ at low temperatures
• Fluorite-related iridate Pr${}_3$IrO${}_7$: Crystal growth, structure, magnetism, thermodynamic, and optical properties