We have used inelastic neutron scattering to determine magnetic excitations in a single-crystal sample of Sr1−xNaxFe2As2. The material's two magnetic phases, which differ in their orthorhombic and tetragonal lattice symmetries, share very similar strengths of magnetic interactions as seen from the high-energy excitations. At low energies, excitations polarized along the c axis are suppressed in the tetragonal magnetic phase, in accordance with the associated reorientation of the ordered moments. Although excitations perpendicular to the c axis are still prominent, only the weak c-axis response exhibits a spin resonant mode in the superconducting state. Our result suggests that c-axis polarized magnetic excitations are important for the formation of the superconductivity, and naturally explains why the critical temperature is suppressed in the tetragonal magnetic phase.
@article{arxiv.1807.04462,
title = {Preferred magnetic excitations in Sr$_{1-x}$Na$_x$Fe$_2$As$_2$},
author = {Jianqing Guo and Li Yue and Kazuki Iida and Kazuya Kamazawa and Lei Chen and Tingting Han and Yan Zhang and Yuan Li},
journal= {arXiv preprint arXiv:1807.04462},
year = {2019}
}
Comments
4 pages, 4 figures; supplementary materials available upon request