arXiv:2205.07005 · Journal of the Physical Society of Japan
S = 2 Quantum Spin Chain with the Biquadratic Exchange Interaction
Tôru Sakai, Takaharu Yamada, Ryosuke Nakanishi, Rito Furuchi, Hiroki Nakano, Hirono Kaneyasu, Kiyomi Okamoto, Takashi Tonegawa
Abstract
The $S=2$ quantum spin chain with the single-ion anisotropy $D$ and the biquadratic exchange interaction $J_{\rm BQ}$ is investigated using the numerical diagonalization of finite-size clusters and the level spectroscopy analysis. It is found that the intermediate-$D$ phase corresponding to the symmetry protected topological (SPT) phase appears in a wide region of the ground state phase diagram. We also obtain the phase diagram at the half of the saturation magnetization which includes the SPT plateau phase.