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

A. E. Taylor; R. A. Ewings; T. G. Perring; J. S. White; P. Babkevich; A. Krzton-Maziopa; E. Pomjakushina; K. Conder; A. T. Boothroyd

doi:10.1103/physrevb.86.094528

arXiv · 1208.3610

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

A. E. Taylor·R. A. Ewings·T. G. Perring·J. S. White·P. Babkevich·A. Krzton-Maziopa·E. Pomjakushina·K. Conder·A. T. Boothroyd

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Abstract

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.

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A. E. Taylor, R. A. Ewings, T. G. Perring, J. S. White, P. Babkevich, A. Krzton-Maziopa, E. Pomjakushina, K. Conder, A. T. Boothroyd. 2012-08-17. Spin-wave excitations and superconducting resonant mode in Cs(x)Fe(2-y)Se2. https://doi.org/10.1103/physrevb.86.094528

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