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arXiv · 1711.01497

Spin excitation anisotropy in optimal-isovalent-doped superconductor BaFe2(As0.7P0.3)2

Ding Hu·Wenliang Zhang·Yuan Wei·Bertrand Roessli·Markos Skoulatos·Louis Pierre Regnault·Genfu Chen·Yu Song·Huiqian Luo·Shiliang Li·Pengcheng Dai
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Abstract

We use neutron polarization analysis to study spin excitation anisotropy in the optimal-isovalent-doped superconductor BaFe2(As0.7P0.3)2 (Tc = 30 K). Different from optimally hole and electron-doped BaFe2As2, where there is a clear spin excitation anisotropy in the paramagnetic tetragonal state well above Tc, we find no spin excitation anisotropy for energies above 2 meV in the normal state of BaFe2(As0.7P0.3)2. Upon entering the superconducting state, significant spin excitation anisotropy develops at the antiferromagnetic (AF) zone center QAF = (1, 0, L = odd), while magnetic spectrum is isotropy at the zone boundary Q = (1, 0, L = even). By comparing temperature, wave vector, and polarization dependence of the spin excitation anisotropy in BaFe2(As0.7P0.3)2 and hole-doped Ba0.67K0.33Fe2As2 (Tc = 38 K), we conclude that such anisotropy arises from spin-orbit coupling and is associated with the nearby AF order and superconductivity.

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Ding Hu, Wenliang Zhang, Yuan Wei, Bertrand Roessli, Markos Skoulatos, Louis Pierre Regnault, Genfu Chen, Yu Song, Huiqian Luo, Shiliang Li, Pengcheng Dai. 2017-11-04. Spin excitation anisotropy in optimal-isovalent-doped superconductor BaFe2(As0.7P0.3)2. https://doi.org/10.1103/physrevb.96.180503

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