Regensburg 2013 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 7: Correlated Electrons: Spin Systems, Itinerant Magnets 1

TT 7.5: Talk

Monday, March 11, 2013, 10:30–10:45, H19

Lifshitz invariants and Z₂-vortex phase in the triangular lattice Kitaev-Heisenberg model — •Ioannis Rousochatzakis, Ulrich Rössler, Jeroen van den Brink, and Maria Daghofer — IFW Dresden, P.O. Box 27 01 16, D-01171 Dresden, Germany

We present our study on the classical Kitaev-Heisenberg Hamiltonian on a triangular lattice, and discuss the presence of an incommensurate non-coplanar phase, which is identified as a lattice of Z₂ vortices. The latter are topological point defects of the SO(3) order parameter in the continuum theory around the nearby Heisenberg antiferromagnet. The defects arise at zero temperature (in contrast to the well known entropic scenario [1]) due to a double-twisting mechanism that is generated by Lifshitz invariants related to spin-orbit coupling. In this respect, this phase is a Z₂ analog to the Z-vortex phases of type-II superconductors [2], the twisted grain boundary phases in liquid crystals [3], and to the Skyrmion lattice phases in chiral magnets [4].
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