Berlin 2015 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 18: Correlated Electrons: Spin Systems and Itinerant Magnets – Frustrated Magnets 2 (jointly with MA)

TT 18.3: Vortrag

Montag, 16. März 2015, 15:30–15:45, H 3005

Weyl spin liquids — •Kevin O’Brien, Maria Hermanns, and Simon Trebst — Institute for Theoretical Physics, University of Cologne, 50937 Cologne, Germany

Topological semimetals – the gapless cousins of topological insulators – have attracted much recent interest. They exhibit bulk features such as gapless Weyl nodes that can be characterized by topological invariants. In addition, they possess gapless surface modes, also called Fermi arcs, which are intimately connected to the bulk features and, thus, topologically protected.

Here we discuss the emergence of such a topological semimetal in three-dimensional generalizations of the Kitaev model. These models describe the fractionalization of spin-orbit entangled moments into Majorana fermions and a Z₂ gauge field. We demonstrate that the Majorana fermions form a Weyl superconductor for the Kitaev model on the recently synthesized hyperhoneycomb structure of β-Li₂IrO₃ in the presence of an external magnetic field. We discuss the topologically protected bulk and surface features of this state, which we dub a Weyl spin liquid.