In integer spin antiferromagnetic Heisenberg chains, the easy plane single-site anisotropy D (>0) destroys the Haldane ground state leading to the large-D phase while the easy axis single-site anisotropy (D <0) drives the Haldane state into the Neel ordered state.In this context, it is an interesting issue to investigate how the ground states of the quantum spin chains are modified if the easy-axis and easy-plane D-terms coexist in a single chain. In the present study, we investigate the ground states of the high spin Heisenberg chains with period 2 modulation of single site anisotropy. It turns out that various phases such as Haldane phase, large-D phase, Tomonaga-Luttinger liquid phase, Neel phases of various structures and ferrimagnetic phase appear depending on the strength of modulation and spin magnitude.
|
|
|
|
