Quantum disordered phase on the frustrated honeycomb lattice

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

PHYSICAL REVIEW B

AMER PHYSICAL SOC

Lugar: New York; Año: 2010 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 $J_2=J_3$ that include the point $J_2=J_3=J_1/2$, corresponding to the highly frustrated point where the classical ground state has macroscopic degeneracy. Using the Linear Spin-Wave, 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 N´eel 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.