Quantum disordered phase on the frustrated honeycomb lattice

D. C. CABRA; C. A. LAMAS; H. D. ROSALES

PHYSICAL REVIEW B

AMER PHYSICAL SOC

Año: 2011 vol. 83 p. 94506 - 94511

1098-0121

In the present paper we study the phase diagram of the Heisenberg model on the honeycomb lattice with antiferromagnetic interactions up to third neighbors along the line J2 = J3 that includes the point J2 = J3 = J1/2, corresponding to the highly frustrated point where the classical ground state has macroscopic degeneracy. Using the linear spin-wave theory and the Schwinger boson technique followed by a mean field decoupling and exact diagonalization for small systems, we find an intermediate phase with a spin gap and short-range Néel correlations in the strong quantum limit (S =1/2). All techniques provide consistent results which allow us to predict the existence of a quantum disordered phase, which may have been observed in recent high-field ESR measurements in manganites.