Quantum spin liquids (QSL) are theoretical states of matter with long-range entanglement and exotic quasiparticles. However, they generally elude quantitative theory, rendering their underlying phases mysterious and hampering efforts to identify experimental QSL states. Here we study triangular lattice resonating valence bond QSL candidate materials KYbSe2 and NaYbSe2. We measure the magnon modes in their 1/3 plateau phase, where quantitative theory is tractable, using inelastic neutron scattering and fit them using nonlinear spin wave theory. We also fit the KYbSe2 heat capacity using high temperature series expansion. Both KYbSe2 fits yield the same magnetic Hamiltonian to within uncertainty, confirming previous estimates and showing the Heisenberg J2/J1 to be an accurate model for these materials. Most importantly, comparing KYbSe2 and NaYbSe2 shows that smaller A-site Na+ ion has a larger J2/J1 ratio. However, hydrostatic pressure applied to KYbSe2 increases the ordering temperature (a result consistent with density functional theory calculations), indicating that pressure decreases J2/J1. These results show how periodic table and hydrostatic pressure can tune the AYbSe2 materials in a controlled way.
@article{arxiv.2207.14785,
title = {Non-linear magnons and exchange Hamiltonians of delafossite proximate quantum spin liquids},
author = {A. O. Scheie and Y. Kamiya and Hao Zhang and Sangyun Lee and A. J. Woods and A. M. Omanakuttan and M. G. Gonzalez and B. Bernu and J. W. Villanova and J. Xing and Q. Huang and Qingming Zhang and Jie Ma and Eun Sang Choi and D. M. Pajerowski and Haidong Zhou and A. S. Sefat and S. Okamoto and T. Berlijn and L. Messio and R. Movshovich and C. D. Batista and D. A. Tennant},
journal= {arXiv preprint arXiv:2207.14785},
year = {2025}
}
Comments
7 pages, 7 figures; 4 pages and 7 additional figures of supplemental information