Magnetic quantum phase transitions of the antiferromagnetic J_{1}-J_{2} Heisenberg model

T. P. Cysne, M. B. Silva Neto

We obtain the complete phase diagram of the antiferromagnetic $J_1$-$J_2$ model, $0\le \alpha =J_2/J1\le 1$, within the framework of the $O(N)$ nonlinear sigma model. We find two…