Spin anisotropy due to spin-orbit coupling in optimally hole-doped Ba$_{0.67}$K$_{0.33}$Fe$_{2}$As$_{2}$

Yu Song; Haoran Man; Rui Zhang; Xingye Lu; Chenglin Zhang; Meng Wang; Guotai Tan; L. -P. Regnault; Yixi Su; Jian Kang; Rafael M. Fernandes; Pengcheng Dai

doi:10.1103/PhysRevB.94.214516

paper

Spin anisotropy due to spin-orbit coupling in optimally hole-doped Ba $_{0.67}$ K $_{0.33}$ Fe $_{2}$ As $_{2}$

arXiv:1612.00379 · doi:10.1103/PhysRevB.94.214516

Abstract

We use polarized inelastic neutron scattering to study the temperature and energy dependence of spin space anisotropies in the optimally hole-doped iron pnictide Ba $_{0.67}$ K $_{0.33}$ Fe $_{2}$ As $_{2}$ ( $T_{c} = 38$ K). In the superconducting state, while the high-energy part of the magnetic spectrum is nearly isotropic, the low-energy part displays a pronouced anisotropy, manifested by a $c$ -axis polarized resonance. We also observe that the spin anisotropy in superconducting Ba $_{0.67}$ K $_{0.33}$ Fe $_{2}$ As $_{2}$ extends to higher energies compared to electron-doped BaFe $_{2 - x} T M_{x}$ As $_{2}$ ( $T M =$ Co, Ni) and isovalent-doped BaFe $_{2}$ As $_{1.4}$ P $_{0.6}$ , suggesting a connection between $T_{c}$ and the energy scale of the spin anisotropy. In the normal state, the low-energy spin anisotropy for optimally hole- and electron-doped iron pnictides onset at temperatures similar to the temperatures at which the elastoresistance deviate from Curie-Weiss behavior, pointing to a possible connection between the two phenomena. Our results highlight the relevance of the spin-orbit coupling to the superconductivity of the iron pnictides.

accepted for publication in Physical Review B, Supplementary information is appended at the end of the arxiv version

Spin anisotropy due to spin-orbit coupling in optimally hole-doped Ba0.67​K0.33​Fe2​As2​

Abstract

Spin anisotropy due to spin-orbit coupling in optimally hole-doped Ba $_{0.67}$ K $_{0.33}$ Fe $_{2}$ As $_{2}$