Metamagnetism in one dimensional systems with edge sharing CuO polyhedra

We study a Heisenberg chain with nearest-neighbor (NN) J1 and next-NN J2 exchange interactions with anisotropies Delta_1 and Delta_2 respectively. We investigate by analytical and numerical methods the region of parameters for which there is a jump in the magnetization M as a function of magnetic field B. Some materials with edge sharing CuO polihedra are candidates to show an abrupt change in M(B).