We report inelastic neutron scattering measurements of magnetic excitations in YbMnSb2, a low-carrier-density Dirac semimetal in which the antiferromagnetic Mn layers are interleaved with Sb layers that host Dirac fermions. We observe a considerable broadening of spin waves, which is consistent with substantial spin fermion coupling. The spin wave damping, γ, in YbMnSb2 is roughly twice larger compared to that in a sister material, YbMnBi2, where an indication of a small damping consistent with theoretical analysis of the spin-fermion coupling was reported. The inter-plane interaction between the Mn layers in YbMnSb2 is also much stronger, suggesting that the interaction mechanism is rooted in the same spin-fermion coupling. Our results establish the systematics of spin-fermion interactions in layered magnetic Dirac materials.
@article{arxiv.2303.02587,
title = {Coupling of magnetism and Dirac fermions in YbMnSb2},
author = {Xiao Hu and Aashish Sapkota and Zhixiang Hu and Andrei T. Savici and Alexander I. Kolesnikov and John M. Tranquada and Cedomir Petrovic and Igor A. Zaliznyak},
journal= {arXiv preprint arXiv:2303.02587},
year = {2023}
}