Dresden 2014 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 95: Focus Session: Theoretical Advances in Interacting Topological Phases (organized by TT)
TT 95.3: Topical Talk
Thursday, April 3, 2014, 16:00–16:30, HSZ 03
Collective Spin-Orbit Physics in j=1/2 Mott Insulators — •Simon Trebst — Universität zu Köln
The greatly enhanced spin-orbit coupling in 5d transition metal oxides can lead to a novel class of Mott insulators in which the local moment is a j=1/2 spin-orbit entangled momentum. The rich physics arising in these novel Mott insulators has been extensively probed in the context of the quasi two-dimensional compounds Sr2IrO4 (square lattice) with regard to superconducting instabilities and Na2IrO3 (honeycomb lattice) in context of possible spin liquid behavior. Here we report on our endeavor to understand the collective states of such spin-orbit entangled j=1/2 momenta when considering other lattice geometries, in particular the triangular lattice motivated by the recent synthesis of Ba3IrTi2O9 and the three-dimensional hyperoctagon lattice in the context of β-Li2IrO3. For the triangular system we find that weak anisotropic Kitaev-like interactions stabilize a Z2-vortex phase. For the hyperoctagon lattice (the premedial lattice of the hyperkagome lattice) we find that strong Kitaev-like couplings give rise to a gapless quantum spin liquid with a Majorana Fermi surface – a highly unusual spin liquid state, which is intimately connected to and protected by the lattice symmetries.