We study the ground state and spin excitations in Ba3MnSb2O9, an easy-plane S = 5/2 triangular lattice antiferromagnet. By combining single-crystal neutron scattering, electric spin resonance (ESR), and spin wave calculations, we determine the frustrated quasi-two-dimensional spin Hamiltonian parameters describing the material. While the material has a slight monoclinic structural distortion, which could allow for isosceles-triangular exchanges and biaxial anisotropy by symmetry, we observe no deviation from the behavior expected for spin waves in the in-plane 120o state. Even the easy-plane anisotropy is so small that it can only be detected by ESR in our study. In conjunction with the quasi-two-dimensionality, our study establishes that Ba3MnSb2O9 is a nearly ideal triangular lattice antiferromagnet with the quasi-classical spin S = 5/2, which suggests that it has the potential for an experimental study of Z- or Z2-vortex excitations.
@article{arxiv.2306.05802,
title = {Static and dynamical properties of the spin-5/2 nearly ideal triangular lattice antiferromagnet Ba3MnSb2O9},
author = {Mingfang Shu and Weicen Dong and Jinlong Jiao and Jiangtao Wu and Gaoting lin and Tao Hong and Huibo Cao and Masaaki Matsuda and Wei Tian and Songxue Chi and Georg Ehlers and Zhongwen Ouyang and Hongwei Chen and Youming Zou and Zhe Qu and Qing Huang and Haidong Zhou and Yoshitomo Kamiya and Jie Ma},
journal= {arXiv preprint arXiv:2306.05802},
year = {2023}
}