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SUMMARY:The nature of the quantum spin-liquid state in Herbertsmithite - M
 atthias Punk\, Universität Innsbruck
DTSTART:20140220T141500Z
DTEND:20140220T151500Z
UID:TALK49848@talks.cam.ac.uk
CONTACT:Dr G Moller
DESCRIPTION:Recent neutron scattering experiments on the layered spin-1/2 
 kagome lattice antiferromagnet Herbertsmithite revealed the first signatur
 e of fractionalized excitations in a quantum spin liquid state. The precis
 e nature of this state remains unclear\, however. Indeed\, mean-field mode
 ls of gapped as well as gapless spin liquids exhibit sharp features in the
  dynamic structure factor\, none of which have been observed in experiment
 .\nIn this talk I'm going to show that several of the experimentally obser
 ved details can be explained by the presence of topological vortex excitat
 ions in a gapped Z2 spin liquid. These so called vison excitations form al
 most flat bands on the kagome lattice and act as a momentum sink for the s
 pin-carrying excitations probed by neutron scattering.
LOCATION:TCM Seminar Room\, Cavendish Laboratory
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