Inversion Phenomena of the Anisotropies of the Hamiltonian and the Wave-Function in the Distorted Diamond Type Spin Chain

We investigate the ground-sate phase diagram of the XXZ version of the S = 1/2 distorted diamond chain by use of the degenerate perturbation theory near the truncation point. In case of the XY -like interaction anisotropy, the phase diagram consists of the Néel phase and the spin-fluid phase. For the Ising-like interaction anisotropy case, it consists of three phases: the ferrimagnetic phase, the Néel phase and the spin-fluid phase. The magnetization in the ferrimagnetic phase is 1/3 of the saturation magnetization. The remarkable nature of the phase diagram is the existence of the Néel phase, although the interaction anisotropy is XY -like. And also, the spin-fluid phase appears in spite of the Ising-like interaction anisotropy. We call these regions “inversion regions”.