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Pressure dependence of the structure and electronic properties of Sr 3 Ir 2 O 7

DOI: 10.1103/PhysRevB.93.174118 DOI Help

Authors: Christian Donnerer (London Centre for Nanotechnology) , Zhuo Feng (University College London (UCL)) , J. G. Vale (London Centre for Nanotechnology, University College London; Laboratory for Quantum Magnetism, Ecole Polytechnique Federal de Lausanne) , S. N. Andreev (Theoretical Physics and Applied Mathematics Department, Ural Federal University) , I. V. Solovyev (Theoretical Physics and Applied Mathematics Department, Ural Federal University; Computational Materials Science Unit, National Institute for Materials Science) , Emily Hunter (University of Edinburgh) , M. Hanfland (European Synchrotron Radiation Facility) , Robin Perry (University College London (UCL)) , H. M. Rønnow (Laboratory for Quantum Magnetism, Ecole Polytechnique Federal de Lausanne) , Malcolm Mcmahon (University of Edinburgh) , V. V. Mazurenko (Theoretical Physics and Applied Mathematics Department, Ural Federal University) , Des Mcmorrow (University College London)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Review B , VOL 93 , PAGES 174118

State: Published (Approved)
Published: May 2016
Diamond Proposal Number(s): 8790

Abstract: We study the structural evolution of Sr3Ir2O7 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 Sr3Ir2O7 at high pressure. In the low-pressure tetragonal phase, we find that the in-plane rotation of the IrO6 octahedra increases with pressure. The calculations further indicate that a bandwidth-driven insulator-metal transition occurs at ∼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 t2g and eg bands. The t2g 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 Sr3Ir2O7.

Journal Keywords: Iridate High-Pressure

Subject Areas: Physics, Materials

Instruments: I15-Extreme Conditions

Other Facilities: ESRF