Dielectric anomalies and interactions in the 3D quadratic band touching Luttinger semimetal Pr${}_2$Ir${}_2$O${}_7$

Abstract

Dirac and Weyl semimetals with linearly crossing bands are the focus of much recent interest in condensed matter physics. Although they host fascinating phenomena, their physics can be understood in terms of weakly interacting electrons. In contrast, more than 40 years ago, Abrikosov pointed out that quadratic band touchings are generically strongly interacting. We have performed terahertz spectroscopy on films of the conducting pyrochlore Pr${}_2$Ir${}_2$O${}_7$, which has been shown to host a quadratic band touching. A dielectric constant as large as $\tilde{\epsilon }/{\epsilon }_0\sim 180$ is observed at low temperatures. In such systems the dielectric constant is a measure of the relative scale of interactions, which are therefore in our material almost two orders of magnitude larger than the kinetic energy. Despite this, the scattering rate exhibits a $T^2$ dependence, which shows that for finite doping a Fermi liquid state survives, however with a scattering rate close to the maximal value allowed.

To appear in Nature Communications (2017)

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• Weyl and Dirac Semimetals in Three Dimensional Solids
• Interplay of Coulomb interactions and disorder in three dimensional quadratic band crossings without time-reversal symmetry and with unequal masses for conduction and valence bands
• d-wave superconductivity and Bogoliubov-Fermi surfaces in Rarita-Schwinger-Weyl semimetals
• Transport in the non-Fermi liquid phase of isotropic Luttinger semimetals
• Thermoelectric and thermal properties of the weakly disordered non-Fermi liquid phase of Luttinger semimetals
• Spontaneous Hall Effect enhanced by local Ir moments in epitaxial Pr${}_2$Ir${}_2$O${}_7$ thin films
• Emergence of topological Mott insulators in proximity of quadratic band touching points
• Anomalous lattice contraction and emergent electronic phases in Bi-doped Eu${}_2$Ir${}_2$O${}_7$
• Possible gapless spin liquid in a rare-earth kagomé lattice magnet Tm${}_3$Sb${}_3$Zn${}_2$O${}_{14}$
• Pr${}_2$Ir${}_2$O${}_7$: when Luttinger semimetal meets Melko-Hertog-Gingras spin ice state
• Unconventional free charge in the correlated semimetal Nd2Ir2O7
• Interacting spin-3/2 fermions in a Luttinger semimetal: Competing phases and their selection in the global phase diagram
• Dielectric and electronic properties of three-dimensional Luttinger semimetals with a quadratic band touching
• Search for plasmons in isotropic Luttinger semimetals
• Dielectric function and plasmons of doped three-dimensional Luttinger semimetals
• Optical response of Luttinger semimetals in the normal and superconducting states
• Superconductivity from Coulomb repulsion in three-dimensional quadratic band touching Luttinger semimetals
• Phonon spectrum of Pr${}_2$Zr${}_2$O${}_7$ and Pr${}_2$Ir${}_2$O${}_7$ as an evidence of coupling of the lattice with electronic and magnetic degrees of freedom
• Transport properties in non-Fermi liquid phases of nodal-point semimetals
• Suppression of long range magnetic ordering and electrical conduction in Y${}_{1.7}$Bi${}_{0.3}$Ir${}_2$O${}_7$ thin film
• Multi-scale Quantum Criticality driven by Kondo-lattice Coupling in Pyrochlore Systems
• Hybrid Dispersion Dirac semimetal and Hybrid Weyl phases in Luttinger Semimetals: A dynamical approach
• Unified description of resistivity and thermopower of Pr${}_2$Ir${}_2$O${}_7$: possible influence of crystal field excitation in a Kondo lattice
• Non-Fermi liquid regime in metallic pyrochlore iridates: Quantum Griffiths singularities
• Weyl-Luttinger phase transition in pyrochlore iridates revealed by Raman scattering
• Quantum paramagnetism in a non-Kramers rare-earth oxide: Monoclinic $\mathrm{P}{\mathrm{r}}_2\mathrm{T}{\mathrm{i}}_2{\mathrm{O}}_7$
• Ubiquitous nematic Dirac semimetal emerging from interacting quadratic band touching system
• Irreducible momentum-space spin structure of Weyl semimetals and its signatures in Friedel oscillations
• Infrared fixed points of higher-spin fermions in topological semimetals
• Quasiuniversality from all-in-all-out Weyl quantum criticality in pyrochlore iridates
• 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
• Impurities in 3D quadratic band-touching Luttinger semimetals : Friedel and RKKY oscillations
• Delta-function-potential junctions with quasiparticles occupying tilted bands with quadratic-in-momentum dispersion
• Transmission through rectangular potentials in semimetals featuring quadratic dispersion
• Kondo Compensation in a Pseudogap Phase: a Renormalization Group Study
• Singular flat bands in three dimensions: Landau level spreading, quantum geometry, and Weyl reconstruction