Berlin 2012 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 10: Focus Session "Topological Transport in Systems with broken Time Inversion Symmetry", Organization: Stefan Blügel (FZ Jülich)

MA 10.3: Hauptvortrag

Montag, 26. März 2012, 16:00–16:30, H 1012

Topological phases with broken time-reversal symmetry in pyrochlore iridates — •Shigeki Onoda — Condensed Matter Theory Laboratory, RIKEN, Wako, Japan

Possible topological phases in pyrochlore iridates are invistigated theoretically. An effective single-orbital tight-binding model is derived by extracting Wannier functions from first-principles band calculations on hypothetical La₂Ir₂O₇ with varying crystal parameters, which mimics the changes only in the radius of rare-earth ions R for R₂Ir₂O₇. Then, introducing the on-site Coulomb repulsion, we solve the effective Hubbard model with the Hartree-Fock approximation. As a function of the Coulomb repulsion, the bandwidth, and the strength of the trigonal distortion, the ground state can exhibit not only metal and Weyl semimetal but also a canted antiferromagentic insulator showing a nonzero uniform magnetization. This is a so-called Chern insulator in three spatial dimensions and exhibits a quantum anomalous Hall effect. Properties of the phase transitions and relevance to experimental systems are also discussed.