Field-induced disorder point in noncollinear Ising spin chains

We perform a theoretical study of a noncollinear Ising ferrimagnetic spin chain inspired by the compound Co(hfac)(2)NITPhOMe. The basic building block of its structure contains one cobalt ion and one organic radical each with a spin 1/2. The exchange interaction is strongly anisotropic and the corresponding axes of anisotropy have a period three helical structure. We introduce and solve a model Hamiltonian for this spin chain. We show that the present compound is very close to a so-called disorder point at which there is a massive ground state degeneracy. We predict the equilibrium magnetization process and discuss the impact of the degeneracy on the dynamical properties by using arguments based on the Glauber dynamics.