Localized spin flop transition in a ladder structure with nonmagnetic impurities

A classical two-leg spin ladder with an antiferromagnetic exchange interact ion and easy axis anisotropy in an external magnetic field exhibits a spin flop transition. A single nonmagnetic impurity introduced into this system allows for the formation of a metastable localized spin flop state at a fie ld above the bulk spin flop field. This state will be symmetrically pinned to the impurity. Two neighboring impurities on the same leg will also resul t in the stabilization of a localized state pinned to the impurities, but i n this case the state is not centered on the impurities. (C) 2001 American Institute of Physics.