Simultaneous Metal-Insulator and Antiferromagnetic Transitions in Orthorhombic Perovskite Iridate Sr0.94Ir0.78O2.68 Single Crystals

Abstract

The orthorhombic perovskite SrIrO3 is a semimetal, an intriguing exception in iridates where the strong spin-orbit interaction coupled with electron correlations tends to impose a novel insulating state. We report results of our investigation of bulk single-crystal Sr0.94Ir0.78O2.68 or Ir-deficient, orthorhombic perovskite SrIrO3. It retains the same crystal structure as stoichiometric SrIrO3 but exhibits a sharp, simultaneous antiferromagnetic (AFM) and metal-insulator (MI) transition at 185 K. Above it, the basal-plane resistivity features an extended regime of almost linear-temperature dependence up to 800 K but the strong electronic anisotropy renders an insulating behavior in the out-of-plane resistivity. The Hall resistivity undergoes an abrupt sign change and grows below 40 K, which along with the Sommerfeld constant of 20 mJ/mole K2 suggests a multiband effect. All results including our first-principles calculations underscore a delicacy of the metallic state in SrIrO3 that is in close proximity to an AFM insulating state. The contrasting ground states in isostructural Sr0.94Ir0.78O2.68 and SrIrO3 illustrate a critical role of even slight lattice distortions in rebalancing the ground state in the iridates. Finally, the observed simultaneous AFM and MI transitions reveal a direct correlation between the magnetic transition and formation of a charge gap in the iridate, which is conspicuously absent in Sr2IrO4.

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Cited by in corpus (8)

• The Challenge of Spin-Orbit-Tuned Ground States in Iridates
• New Evidence for a Low-Temperature Magnetic Ground State in Double-Perovskite Iridates with Ir5+(5d4) Ions
• Growth and engineering of perovskite SrIrO3 thin films
• Doping Evolution of Magnetic Order and Magnetic Excitations in (Sr${}_{1-x}$La${}_x$)${}_3$Ir${}_2$O${}_7$
• Strain-dependent Insulating State and Kondo Effect in Epitaxial SrIrO${}_3$ Films
• Emergent Magnetism at the 3$d$-5$d$ Interface: SrMnO${}_3/$SrIrO${}_3$
• Flux growth of Sr(n+1)Ir(n)O(3n+1) [n=1, 2, infinity] crystals
• Coexistence of insulator-like paramagnon and metallic spin-orbit exciton modes in SrIrO${}_3$