Dresden 2017 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 42: Correlated Electrons: Frustrated Magnets - Strong Spin-Orbit Coupling 2
TT 42.2: Vortrag
Mittwoch, 22. März 2017, 09:45–10:00, HSZ 304
Three-band Hubbard model for Na2IrO3: Topological insulator, zigzag antiferromagnet, and Kitaev-Heisenberg material — •Stephan Rachel1, Manuel Laubach1, Ronny Thomale2, and Johannes Reuther3 — 1TU Dresden, Institut für Theoretische Physik — 2Universität Würzburg, Institut für Theoretische Physik — 3FU Berlin & Helmholtz-Zentrum Berlin
Na2IrO3 was one of the first materials proposed to feature the Kane-Mele type topological insulator phase. About the same time it was claimed that the very same material is in a Mott insulating phase which is described by the Kitaev-Heisenberg (KH) model. First experiments indeed revealed Mott insulating behavior in conjunction with antiferromagnetic long-range order. Further refined experiments established antiferromagnetic order of zigzag type which is not captured by the KH model. Since then several extensions and modifications of the KH model were proposed in order to describe the experimental findings. Here we suggest that adding charge fluctuations to the KH model represents an alternative explanation of zigzag antiferromagnetism. Moreover, a phenomenological three-band Hubbard model unifies all the pieces of the puzzle: topological insulator physics for weak and KH model for strong electron-electron interactions. And at moderate interaction strength we find a zigzag antiferromagnet.