Nonsymmorphic Dirac semimetal and carrier dynamics in doped spin-orbit-coupled Mott insulator Sr${}_2$IrO${}_4$

Abstract

A Dirac fermion emerges as a result of interplay between symmetry and topology in condensed matter. Current research moves towards investigating the Dirac fermions in the presence of manybody effects in correlated system. Here, we demonstrate the emergence of correlation-induced symmetry-protected Dirac semimetal state in the lightly-doped spin-orbit-coupled Mott insulator Sr${}_2$IrO${}_4$. We find that the nonsymmorphic crystalline symmetry stabilizes a Dirac line-node semimetal and that the correlation-induced symmetry-breaking electronic order further leads to a phase transition from the Dirac line-node to a Dirac point-node semimetal. The latter state is experimentally confirmed by angle-resolved photoemission spectroscopy and terahertz spectroscopy on Sr${}_2$(Ir,Tb)O${}_4$ and (Sr,La)${}_2$IrO${}_4$. Remarkably, the electrodynamics of the massless Dirac carriers is governed by the extremely small scattering rate of about 6 cm${}^{-1}$ even at room temperature, which is iconic behavior of relativistic quasiparticles. Temperature-dependent changes in electrodynamic parameters are also consistently explained based on the Dirac point-node semimetal state.

6 pages, 4 figures + Supplemental Material

References in corpus (12)

• The electronic properties of graphene
• Novel Jeff = 1/2 Mott State Induced by Relativistic Spin-Orbit Coupling in Sr2IrO4
• Temperature dependent transport in suspended graphene
• Theory of Intertwined Orders in High Temperature Superconductors
• Classification of stable three-dimensional Dirac semimetals with nontrivial topology
• 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 $\infty$)
• Fermi Arcs in a Doped Pseudospin-1/2 Heisenberg Antiferromagnet
• Screening induced temperature dependent transport in 2D graphene
• The magnetic and crystal structures of Sr2IrO4: A neutron diffraction study
• A structural distortion induced magneto-elastic locking in Sr${}_2$IrO${}_4$ revealed through nonlinear optical harmonic generation
• Unidirectional spin density wave state in metallic (Sr1-xLax)2IrO4
• Dual topological nodal line and nonsymmorphic Dirac semimetal in three dimensions

Cited by in corpus (2)

• Low-energy electrodynamics of Dirac semimetal phases in the doped Mott insulator Sr${}_2$IrO${}_4$
• Three-dimensional Stacking of Canted Antiferromagnetism and Pseudospin Current in Undoped Sr${}_2$IrO${}_4$: Symmetry Analysis and Microscopic Model Realization