Magnetic Field Induced Exotic Phases in Isotropic Frustrated Spin-1/2   chain
  The frustrated isotropic $J_1-J_2$ model with ferromagnetic $J_1$ and anti-ferromagnetic $J_2$ interactions in presence of an axial magnetic field shows many exotic phases, such as vector chiral and multipolar phases. The existing studies of the phase boundaries of these systems are based on the indirect evidences such as correlation functions {\it etc}. In this paper, the phase boundaries of these exotic phases are calculated based on order parameters and jumps in the magnetization. In the strong magnetic field, $Z_2$ symmetry is broken, therefore, order parameter of the vector chiral phase is calculated using the broken symmetry states. Our results obtained using the modified density matrix renormalization group and exact diagonalization methods, suggest that the vector chiral phase exist only in narrow range of parameter space $J_2/J_1$. 
Aslam Parvej and Manoranjan Kumar
cond-mat.str-el