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FIELD Phys:Condensed Matter Physics
DATE January 11 (Fri), 2019
TIME 14:00-16:00
PLACE 1424
SPEAKER Jong Yeon Lee
HOST Kang, Byungmin
INSTITUTE Harvard University
TITLE Emergent O(4) Symmetry and Signatures of Deconfined Quantum Critical Point in Shastry-Sutherland Lattice Material SrCu2(BO3)2
ABSTRACT Abstract: We study the possibility of a deconfined quantum phase transition in the two dimensional Shastry-Sutherland spin model, using both numerical and field theoretic techniques. We argue that the quantum phase transition between a two fold degenerate plaquette valence bond solid (pVBS) order and Neel order may be described by a deconfined quantum critical point (DQCP) with emergent O(4) symmetry. Further, using the infinite density matrix renormalization group (iDMRG) numerical technique, we verify the emergence of an intermediate pVBS order, between the dimer and Neel ordered phases. By analyzing the correlation length spectrum for different orders, we provide evidence for deconfinement and emergent O(4) symmetry at the phase transition between the pVBS and N\'eel orders. Such a phase transition has been reported in the recent pressure tuned experiments in the Shastry-Sutherland lattice material SrCu2(BO3)2. The non-symmorphic lattice structure of the Shastry-Sutherland compound leads to extinction points in the scattering, at which we predict sharp signatures for DQCP in both phonon and magnon spectra associated to the spinon continuua. Our result would guide the experimental search for DQCP in quantum magnets.
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