Elucidating the nature of the magnetism of a high-temperature superconductor is crucial for establishing its pairing mechanism. The parent compounds of the cuprate and iron-pnictide superconductors exhibit N\'eel and stripe magnetic order, respectively. However, FeSe, the structurally simplest iron-based superconductor, shows nematic order (Ts = 90 K), but not magnetic order in the parent phase, and its magnetic ground state is intensely debated. Here, we report inelastic neutron-scattering experiments that reveal both stripe and N\'eel spin fluctuations over a wide energy range at 110 K. On entering the nematic phase, a substantial amount of spectral weight is transferred from the N\'eel to the stripe spin fluctuations. Moreover, the total fluctuating magnetic moment of FeSe is ~ 60% larger than that in the iron pnictide BaFe2As2. Our results suggest that FeSe is a novel S = 1 nematic quantum-disordered paramagnet interpolating between the N\'eel and stripe magnetic instabilities.
@article{arxiv.1511.02485,
title = {Magnetic ground state of FeSe},
author = {Qisi Wang and Yao Shen and Bingying Pan and Xiaowen Zhang and K. Ikeuchi and K. Iida and A. D. Christianson and H. C. Walker and D. T. Adroja and M. Abdel-Hafiez and Xiaojia Chen and D. A. Chareev and A. N. Vasiliev and Jun Zhao},
journal= {arXiv preprint arXiv:1511.02485},
year = {2016}
}
Comments
Supplementary information included; accepted by Nature Communications