Berlin 2012 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 26: Transport: Topological Insulators 3 (jointly with HL and MA)

TT 26.10: Talk

Wednesday, March 28, 2012, 12:00–12:15, BH 334

Strong Correlations in a Generic Topological Insulator: The Transition-Metal Oxide Na₂IrO₃ — •Manuel Laubach¹, Ronny Thomale², Stephan Rachel³, and Werner Hanke¹ — ¹Theoretical Physics, University of Würzburg, D-97074 Würzburg — ²Department of Physics, McCullough Building, Stanford University, Stanford, California 94305-4045 — ³Department of Physics, Yale University, New Haven, CT 06520, USA

A key recent advancement in condensed-matter physics is to study the interplay between nontrivial topology and electronic correlations. In 5d transition-metal oxides, both the spin-orbit interaction and the electron correlation emerge at comparable orders of magnitude. In these systems, a variety of specifically tailored crystal structures are available, enabling the design of robust topological insulators. In this work, we study theoretically a monolayer of the 5d-compound Na₂IrO₃, modeled by a Hubbard-type of Hamiltonian on a honeycomb lattice where the spin symmetry is not conserved. Based on a variational cluster approach (VCA), the zero temperature phase diagram is obtained. We can identify, through an increase of the Hubbard U, the transition from a quantum spin Hall insulator to either a spin liquid phase or an antiferromagnetic insulating phase, depending on the strength of the spin-orbit coupling. We illustrate the evolution of the quasiparticle spectral function for bulk and edge-states upon variation of system parameters.