Electron and hole doping in the relativistic Mott insulator Sr2IrO4: A first-principles study using band unfolding technique

Peitao Liu, Michele Reticcioli, Bongjae Kim, Alessandra Continenza, Georg Kresse, D. D. Sarma, Xing-Qiu Chen, and Cesare Franchini
Phys. Rev. B 94, 195145 – Published 28 November 2016

Abstract

We study the effects of dilute La and Rh substitutional doping on the electronic structure of the relativistic Mott insulator Sr2IrO4 using fully relativistic and magnetically noncollinear density functional theory with the inclusion of an on-site Hubbard U. To model doping effects, we have adopted the supercell approach, that allows for a realistic treatment of structural relaxations and electronic effects beyond a purely rigid band approach. By means of the band unfolding technique we have computed the spectral function and constructed the effective band structure and Fermi surface (FS) in the primitive cell, which are readily comparable with available experimental data. Our calculations clearly indicate that La and Rh doping can be interpreted as effective electron and (fractional) hole doping, respectively. We found that both electron and hole doping induce an insulating-to-metal transition (IMT) but with different characteristics. In Sr2xLaxIrO4 the IMT is accompanied by a moderate renormalization of the electronic correlation substantiated by a reduction of the effective on-site Coulomb repulsion UJ from 1.6 eV (x=0) to 1.4 eV (metallic regime of x=12.5%). The progressive closing of the relativistic Mott gap leads to the emergence of connected elliptical electron pockets at (π/2,π/2) and less intense features at X on the Fermi surface. The average ordered magnetic moment is slightly reduced upon doping, but the canted antiferromagnetic state is perturbed on the Ir-O planes located near the La atoms. The substitution of Ir with the nominally isovalent Rh is accompanied by a substantial hole transfer from the Rh site to the nearest-neighbor Ir sites. This shifts down the chemical potential, creates almost circular disconnected hole pockets in the FS, and establishes the emergence of a two-dimensional metallic state formed by conducting Rh planes intercalated by insulating Ir planes. Finally, our data indicate that hole doping causes a flipping of the in-plane net ferromagnetic moment on the Rh plane and induces a magnetic transition from the antiferromagnetic (AF)-I to the AF-II ordering.

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  • Received 28 June 2016
  • Revised 9 November 2016

DOI:https://doi.org/10.1103/PhysRevB.94.195145

©2016 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Peitao Liu1,2, Michele Reticcioli1, Bongjae Kim1, Alessandra Continenza3, Georg Kresse4, D. D. Sarma5, Xing-Qiu Chen2, and Cesare Franchini1,*

  • 1University of Vienna, Faculty of Physics and Center for Computational Materials Science, Sensengasse 8/8, A-1090 Vienna, Austria
  • 2Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
  • 3Department of Information Engineering, Computer Science and Mathematics, University of L'Aquila, Via Vetoio, 67100 Coppito (AQ), Italy
  • 4University of Vienna, Faculty of Physics and Center for Computational Materials Science, Sensengasse 8/12, A-1090 Vienna, Austria
  • 5Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore-560012, India

  • *Corresponding author: cesare.franchini@univie.ac.at

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Issue

Vol. 94, Iss. 19 — 15 November 2016

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