Low-energy electrodynamics of Dirac semimetal phases in the doped Mott insulator Sr${}_2$IrO${}_4$

Abstract

Correlated Dirac semimetal phases emerge in lightly doped (Tb- or La-doped) Mott insulator Sr${}_2$IrO${}_4$, where a d-wave symmetry-breaking order underlying a pseudogap plays a crucial role in determining the nature of Dirac degeneracy, i.e., whether it is a Dirac line node or Dirac point node. Here, using a realistic five-orbital tight-binding model with a Hubbard U and a semiclassical Boltzmann transport theory, we systematically study the low-energy electrodynamic properties of the Dirac semimetal phases in the paramagnetic lightly doped Sr${}_2$IrO${}_4$. We investigate the effects of the d-wave electronic order and electron doping concentration on the electronic band structures and optical properties of various Dirac semimetal phases. We calculate the intraband optical conductivity and obtain electrodynamic parameters of dc conductivity, scattering rate, and Drude weight for three Dirac semimetal phases: two are Dirac point-node states observed in the 3% Tb-doped and 5% La-doped Sr${}_2$IrO${}_4$, and the other is a Dirac line-node state. Our results show that the temperature dependence of the electrodynamic parameters is strong in the Tb-doped system while weak in the La-doped and Dirac line-node systems, which are consistent with available experimental data. Moreover, using the low-energy effective theory, we also compare the temperature-dependent screening effect in the Tb- and La-doped systems using graphene as a reference. Our paper provides valuable insight for understanding the transport and optical properties of correlated Dirac semimetal phases in the doped Sr${}_2$IrO${}_4$.

12 pages, 6 figures

References in corpus (13)

• The electronic properties of graphene
• Ultrahigh electron mobility in suspended graphene
• Mott Insulators in the Strong Spin-Orbit Coupling Limit: From Heisenberg to a Quantum Compass and Kitaev Models
• Novel Jeff = 1/2 Mott State Induced by Relativistic Spin-Orbit Coupling in Sr2IrO4
• Temperature dependent transport in suspended graphene
• Twisted Hubbard Model for Sr2IrO4: Magnetism and Possible High Temperature Superconductivity
• Hydrodynamics of electrons in graphene
• Screening induced temperature dependent transport in 2D graphene
• Microscopic study of spin-orbit-induced Mott insulator in Ir oxides
• Semiclassical framework for the calculation of transport anisotropies
• Density dependent electrical conductivity in suspended graphene: Approaching the Dirac point in transport
• Charge transport in gapless chiral electron systems with arbitrary band dispersion
• Nonsymmorphic Dirac semimetal and carrier dynamics in doped spin-orbit-coupled Mott insulator Sr${}_2$IrO${}_4$

Cited by in corpus (1)

• Three-dimensional Stacking of Canted Antiferromagnetism and Pseudospin Current in Undoped Sr${}_2$IrO${}_4$: Symmetry Analysis and Microscopic Model Realization