Pressure dependence of the structure and electronic properties of Sr3Ir2O7

Abstract

We study the structural evolution of Sr${}_3$Ir${}_2$O${}_7$ as a function of pressure using x-ray diffraction. At a pressure of 54 GPa at room temperature, we observe a first-order structural phase transition, associated with a change from tetragonal to monoclinic symmetry, and accompanied by a 4% volume collapse. Rietveld refinement of the high-pressure phase reveals a novel modification of the Ruddlesden-Popper structure, which adopts an altered stacking sequence of the perovskite bilayers. As the positions of the oxygen atoms could not be reliably refined from the data, we use density functional theory (local-density approximation+$U$+spin orbit) to optimize the crystal structure, and to elucidate the electronic and magnetic properties of Sr${}_3$Ir${}_2$O${}_7$ at high pressure. In the low-pressure tetragonal phase, we find that the in-plane rotation of the IrO${}_6$ octahedra increases with pressure. The calculations further indicate that a bandwidth-driven insulator-metal transition occurs at $\sim$20 GPa, along with a quenching of the magnetic moment. In the high-pressure monoclinic phase, structural optimization resulted in complex tilting and rotation of the oxygen octahedra, and strongly overlapping $t_{2g}$ and $e_g$ bands. The $t_{2g}$ bandwidth renders both the spin-orbit coupling and electronic correlations ineffectual in opening an electronic gap, resulting in a robust metallic state for the high-pressure phase of Sr${}_3$Ir${}_2$O${}_7$.

9 pages, 12 figures, accepted in PRB

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• A weakly correlated Fermi liquid state with a small Fermi surface in lightly doped Sr${}_3$Ir${}_2$O${}_7$
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Cited by in corpus (14)

• The Challenge of Spin-Orbit-Tuned Ground States in Iridates
• Pressure-tuning of bond-directional exchange interactions and magnetic frustration in hyperhoneycomb iridate $\beta$-$\mathrm{L}{\mathrm{i}}_2\mathrm{Ir}{\mathrm{O}}_3$
• Persistent Insulator: Avoidance of Metallization at Megabar Pressures in Strongly Spin-Orbit-Coupled Sr2IrO4
• First-order structural transition and pressure-induced lattice/phonon anomalies in Sr${}_2$IrO${}_4$
• Structural, electronic, and magnetic properties of nearly-ideal $J_{\mathrm{eff}}$ $=$ 1/2 iridium halides
• Lattice frustration in spin-orbit Mott insulator Sr3Ir2O7 at high pressure
• High-pressure insulator-to-metal transition in Sr${}_3$Ir${}_2$O${}_7$ studied by x-ray absorption spectroscopy
• Role of Square Planar Coordination in the Magnetic Properties of Na4IrO4
• Resonant inelastic x-ray scattering of magnetic excitations under pressure
• Decoupling of magnetism and electric transport in single-crystal (Sr1-xAx)2IrO4 (A = Ca or Ba)
• Pressure-induced transition from Jeff=1/2 to S=1/2 states in CuAl2O4
• Critical fluctuations in the spin-orbit Mott insulator Sr${}_3$Ir${}_2$O${}_7$
• Exploring the energy landscape of resistive switching in antiferromagnetic Sr(3)Ir(2)O(7)
• Stressor-Layer-Induced Elastic Strain Sharing in SrTiO3 Complex Oxide Sheets