Investigation of dynamical excitations is difficult but crucial to the understanding of many exotic quantum phenomena discovered in quantum materials. This is particularly true for highly frustrated quantum antiferromagnets whose dynamical properties deviate strongly from theoretical predictions made based on the spin-wave or other approximations. Here we present a large-scale numerical calculation on the dynamical correlation functions of spin-1/2 triangular Heisenberg model using a state-of-the-art tensor network renormalization group method. The calculated results allow us to gain for the first time a comprehensive picture on the nature of spin excitation spectra in this highly frustrated quantum system. It provides a quantitative account for all the key features of the dynamical spectra disclosed by inelastic neutron scattering measurements for Ba₃CoSb₂O₉, revealing the importance of the interplay between low- and high-energy excitations and its renormalization effect to the low-energy magnon bands and high-energy continuums. We identify the longitudinal Higgs modes in the intermediate-energy scale and predict the energy and momentum dependence of spectral functions along the three principal axes that can be verified by polarized neutron scattering experiments. Furthermore, we find that the spin excitation spectra weakly depend on the anisotropic ratio of the antiferromagnetic interaction. 

廖海军，中国科学院物理研究所副研究员，博士生导师。2009年至2014年在中国人民大学学习，获得学士、博士学位。2014年-2017年，在中国科学院物理研究所向涛院士课题组从事博士后研究。2017年-至今，在中科院物理所工作，2021年入选中科院青促会会员。主要研究兴趣是发展新的张量重正化群方法，并运用它研究阻挫磁性、高温超导等强关联系统，以及各种经典统计模型等。至今在PRL、PRX等国际一流期刊发表论文多篇。