Honeycomb antiferromagnet with a triply degenerate dimer ground state

Abstract

We present an antiferromagnetic quantum spin-1/2 model on honeycomb lattice. It has two parts, one of which is the usual nearest-neighbor Heisenberg model. The other part is a certain multiple spin interaction term, introduced by us, which is exactly solvable for the ground state. Without the Heisenberg part, the model has an exact threefold degenerate dimer ground state. This exact ground state is also noted to exist for the general spin-S case. For the spin-1/2 case, we further carry out the triplon analysis in the ground state, to study the competition between the Heisenberg and the multiple spin interactions. This approximate calculation exhibits a continuous quantum phase transition from the dimer order to Néel order.

6+ pages, 10 figures, submitted to Phys. Rev. B

References in corpus (5)

• "Deconfined" quantum critical points
• Evidence for deconfined quantum criticality in a two-dimensional Heisenberg model with four-spin interactions
• Quantum magnetism and criticality
• Spin-gap phase of a quantum spin system on a honeycomb lattice
• Fourfold degenerate columnar-dimer ground state in square lattice antiferromagnets

Cited by in corpus (8)

• Spiral order by disorder and lattice nematic order in a frustrated Heisenberg antiferromagnet on the honeycomb lattice
• Exotic disordered phases in the quantum $J_1-J_2$ model on the honeycomb lattice
• Bond-operators and triplon analysis for spin-S dimer antiferromagnets
• Spin liquids in graphene
• Neel to staggered dimer order transition in a generalized honeycomb lattice Heisenberg model
• Triplon mean-field analysis of an antiferromagnet with degenerate Shastry-Sutherland ground states
• Exact staggered dimer ground state and its stability in a two-dimensional magnet
• Quantum to classical transition in the ground state of a spin-$S$ quantum antiferromagnet