Schwinger boson theory of quantum frustrated two-dimensional antiferromagnets

The frustrated two-dimensional Heisenberg models are very important models in condensed matter physics being studied a lot using numerical techniques such as quantum Monte Carlo method (QMC) and density matrix renormalization group (DMRG). Hence, we have studied the phase transition and spin transport in the S=1/2 two-dimensional Heisenberg antiferromagnetic model in different types of lattices and with second-neighbor interactions using the Schwinger boson representation of spins operators, which is know to be an important analytical tool . We calculate the critical parameters and the spin conductivity and analyze the behavior of the AC spin conductivity on the critical line of separation of the different phases of this model.