Hall 123

Neel to Valence-Bond Solid transition on the honeycomb

Sumiran Pujari

TIFR

We study a spin-1/2 SU(2) JQ-Hamiltonian on the honeycomb lattice with nearest-neighbour antiferromagnetic exchange J that favors Neel order, and
competing 6-spin interactions Q which favor a valence bond solid (VBS) state. We present numerical evidence from quantum Monte-Carlo simulations for a direct continuous quantum phase transition between Neel and VBS states, with critical exponents and logarithmic violations of scaling consistent with those at analogous deconfined critical points on the square lattice. Although this strongly suggests a description in terms
of deconfined criticality, the measured three-fold anisotropy of the phase of the VBS order parameter shows near-marginal behaviour at the critical
point in contrast to the usual deconfined criticality scenario.