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. 945061 - 945065

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.