Ba3CoSb2O9 approximates the two-dimensional spin-1/2 triangular-lattice Heisenberg antiferromagnet. This compound displays magnetic-field-induced quantum phase transitions, including the 1/3-magnetization-plateau, but its magnetization processes for the magnetic field H parallel and perpendicular to the c axis are different due to the weak easy-plane anisotropy and the weak interlayer antiferromagnetic exchange interaction. To elucidate how the quantum phase transitions change between these two field directions, we measured the field-angle dependence of the magnetization process in Ba3CoSb2O9 using pulsed high magnetic fields. We compared obtained magnetic field-field angle phase diagram with those obtained by the large-size cluster mean-field method combined with a scaling scheme and the semiclassical theory. We also found a narrow 1/3-magnetization plateau and a high-field transition with a small magnetization jump for H∥c, not observed in the previous studies.
@article{arxiv.2207.09075,
title = {Field-orientation dependence of quantum phase transitions in the S=1/2 triangular-lattice antiferromagnet Ba$_3$CoSb$_2$O$_9$},
author = {Kazuki Okada and Hidekazu Tanaka and Nobuyuki Kurita and Daisuke Yamamoto and Akira Matsuo and Koichi Kindo},
journal= {arXiv preprint arXiv:2207.09075},
year = {2023}
}