Continuum of spin excitations observed in inelastic neutron scattering experiments are often considered as a strong evidence of quantum spin liquid formation. When quantum spin liquid is indeed the ground state of a disorder-free magnetic compound, the elementary excitation is no longer the conventional spin waves (magnons). Instead, the magnons fractionalize into spinons, leaving only a two-spinon continuum detectable in inelastic neutron scattering experiments. For a clean ordered antiferromagnet, it was unclear if we can observe a continuous spectrum similar to the ones in a quantum spin liquid state. Here we show that the magnetically ordered state in Na2BaCo(PO4)2 is able to host a spin excitation continuum induced by strong quantum fluctuations. Thus, a second thought is necessary when concluding such continuum as signature of quantum spin liquid in new material explorations.
@article{arxiv.2402.07730,
title = {Continuum of spin excitations in an ordered magnet},
author = {Jieming Sheng and Le Wang and Wenrui Jiang and Han Ge and Nan Zhao and Tiantian Li and Maiko Kofu and Dehong Yu and Wei Zhu and Jia-Wei Mei and Zhentao Wang and Liusuo Wu},
journal= {arXiv preprint arXiv:2402.07730},
year = {2025}
}