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Berlin 2015 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 87: Low-dimensional systems: Topological order 2 (TT with DS/HL/MA/O)

HL 87.8: Talk

Thursday, March 19, 2015, 17:00–17:15, H 3010

Quasiparticle interference patterns from different impurities on the surface of pyrochlore iridates: signatures of the Weyl phase — •Fabian Lambert1, Andreas Schnyder2, Roderich Moessner3, and Ilya Eremin11Institut für Theoretische Physik III, Ruhr-Universität Bochum, D-44801 Bochum, Germany — 2Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany — 3Max Planck Institute for the Physics of Complex Systems, D-01187 Dresden, Germany

Weyl semi-metals exhibit topologically protected surface Fermi arcs, which pairwise connect projections of bulk band touchings in the surface Brillouin zone. The nontrival spin and orbital character of these topological surface states can be tested experimentally using quasiparticle interference (QPI) measurements. Here, we compute the QPI patterns for a Hubbard Hamiltonian on a pyrochlore lattice. For weak impurity potentials, the QPI patterns can be computed within the First Born approximation. To account for the antiferromangetic spin configuration of R2Ir2O7, we treat the Hubbard interaction at the mean-field level. In the antiferromagnetic state the quadratic band touching of the model is split into eight linear band touchings, each of which carries a non-trivial Chern number, thereby realizing a Weyl phase with broken time- reversal symmetry. Using exact diagonalization, we compute the surface spectrum and quasiparticle interference patterns of this Weyl phase for various surface impurities. We show that the spin and orbital texture of the surface states can be inferred from the absence of certain backscattering processes and from the symmetries of the QPI features.

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