Effect of monomer-monomer interactions on the phase diagrams of the S=1/2 distorted diamond type quantum spin chain

Okamoto, Kiyomi*; Tonegawa, Takashi*; Sakai, Toru

By use of mainly the exact diagonalization and the level spectroscopy method, we investigate the ground-state phase diagrams of the S=1/2 distorted diamond type quantum spin chain with the monomer-monomer interactions and ferromagnetic interactions. The magnetization plateau at 1/3 of the saturation magnetization was revealed to vanish in the region where the ferromagnetic interaction is rather strong.