Inversion phenomena of the anisotropies of the Hamiltonian and the wave-function in the distorted diamond type spin chain Original Research Article

We investigate the ground-state phase diagram of the XXZ version of the S=1/2 distorted diamond chain by the use of 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’.