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SUMMARY:Two-dimensional Valence Bond Solid (AKLT) states from t2g electron
 s - Maciej Koch-Janusz\, Weizmann Institute
DTSTART:20150129T141500Z
DTEND:20150129T151500Z
UID:TALK57183@talks.cam.ac.uk
CONTACT:Dr G Moller
DESCRIPTION:Two-dimensional AKLT model on a honeycomb lattice has been sho
 wn to be a universal resource for quantum computation. In this valence bon
 d solid\, however\, the spin interactions involve higher powers of the Hei
 senberg coupling (Si*Sj)^n\, making these states seemingly unrealistic on 
 bipartite lattices\, where one expects a simple antiferromagnetic order. W
 e show that those interactions can be generated by orbital physics in mult
 iorbital Mott insulators. We focus on t2g electrons on the honeycomb latti
 ce and propose a physical realization of the spin-3/2 AKLT state. We find 
 a phase transition from the AKLT to the Neel state on increasing Hund's ru
 le coupling\, which is confirmed by density matrix renormalization group (
 DMRG) simulations. An experimental signature of the AKLT state consists of
  protected\, free spins-1/2 on lattice vacancies\, which may be detected i
 n the spin susceptibility.
LOCATION:TCM Seminar Room\, Cavendish Laboratory
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