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 Neel phase and the spin-fluid phase. For the Ising-like
interaction anisotropy case, it consists of three phases: the ferrimagnetic
phase, the Neel 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 Neel 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".Comment: 7 pages, 4 figure