Spin-wave excitations and superconducting resonant mode in Cs(x)Fe(2-y)Se2

Journal article

We report neutron inelastic scattering measurements on the normal and superconducting states of single-crystalline Cs0.8Fe1.9Se2. Consistent with previous measurements on Rb(x)Fe(2-y)Se2, we observe two distinct spin excitation signals: (i) spin-wave excitations characteristic of the block antiferromagnetic order found in insulating A(x)Fe(2-y)Se2 compounds, and (ii) a resonance-like magnetic peak localized in energy at 11 meV and at an in-plane wave vector of (0.25, 0.5). The resonance peak increases below Tc = 27 K, and has a similar absolute intensity to the resonance peaks observed in other Fe-based superconductors. The existence of a magnetic resonance in the spectrum of Rb(x)Fe(2-y)Se2 and now of Cs(x)Fe(2-y)Se2 suggests that this is a common feature of superconductivity in this family. The low energy spin-wave excitations in Cs0.8Fe1.9Se2 show no measurable response to superconductivity, consistent with the notion of spatially separate magnetic and superconducting phases.

Authors: Taylor, A; Ewings, R; Perring, T; White, J; Babkevich, P

• Publication status: Published
• Journal: Phys. Rev. B
• Volume: 86
• Issue: 9
• Pages: 094528
• Publication date: 2012-08-17
• DOI: 10.1103/PhysRevB.86.094528
• EISSN: 1550-235X
• ISSN: 1098-0121
• Language: English
• Keywords: cond-mat.supr-con