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Abstract

With the help of the bond operator representation for three S spins, we study the effective Hamiltonian and the phase diagram of a generalized spin-1/2 distorted diamond chain. In the weak- intertriangle-coupling limit, the magnetism of the effective Hamiltonian is studied with second-order perturbation theory and mean-field decoupling. Various phases such as the spin- fluid phase, the dimerized phase and the ferrimagnetic phase are shown to compete. For larger intertriangle interactions, the spin-fluid phase and the dimerized phase can be also described by the effective spin-orbital model and the region of the dimerized phase enlarges around the symmetric point of J(1) = J(2) = J(3) (J(1), J(2) and J(3) are the intratriangle interactions). The magnetization plateaus at 1/3M(s) and 2/3M(s) in the magnetic field are also studied.