Magnetic interactions in Cr spinels

Abstract Exchange coupling constants J n are estimated for ACr 2 X 4 ( A = Zn , Cd ; X = O , S, Se) spinels by mapping the energy of spin spirals calculated within the LSDA + U approximation onto an effective Heisenberg model. The calculations reproduce the change of the sign of the exchange coupling between Cr nearest neighbors (NN) from AFM in the O spinels to FM in S and Se ones. The exchange interaction between more distant Cr neighbors becomes stronger with the increase of the X atomic number ( Z X ).