paper

Quantum phase diagram of the spin- Heisenberg model on the honeycomb lattice

arXiv:1508.00515 · doi:10.1103/PhysRevB.92.195110

Abstract

Strongly correlated systems with geometric frustrations can host the emergent phases of matter with unconventional properties. Here, we study the spin Heisenberg model on the honeycomb lattice with the antiferromagnetic first- () and second-neighbor () interactions () by means of density matrix renormalization group (DMRG). In the parameter regime , the system sustains a Néel antiferromagnetic phase. At the large side , a stripe antiferromagnetic phase is found. Between the two magnetic ordered phases , we find a \textit{non-magnetic} intermediate region with a plaquette valence-bond order. Although our calculations are limited within unit-cell width on cylinder, we present evidence that this plaquette state could be a strong candidate for this non-magnetic region in the thermodynamic limit. We also briefly discuss the nature of the quantum phase transitions in the system. We gain further insight of the non-magnetic phases in the spin- system by comparing its phase diagram with the spin- system.

7 pages, 10 figures

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