The S=2 quantum spin chain with the single-ion anisotropy D and the biquadratic exchange interaction JBQ 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.
@article{arxiv.2205.07005,
title = {S=2 Quantum Spin Chain with the Biquadratic Exchange Interaction},
author = {Tôru Sakai and Takaharu Yamada and Ryosuke Nakanishi and Rito Furuchi and Hiroki Nakano and Hirono Kaneyasu and Kiyomi Okamoto and Takashi Tonegawa},
journal= {arXiv preprint arXiv:2205.07005},
year = {2022}
}