Spin Gap and Resonance at the Nesting Wavevector in Superconducting FeSe0.4Te0.6

Abstract

Neutron scattering is used to probe magnetic excitations in FeSe_{0.4}Te_{0.6} (T_c=14 K). Low energy spin fluctuations are found with a characteristic wave vector $(0.5,0.5,L)$ that corresponds to Fermi surface nesting and differs from Q_m=(δ,0,0.5) for magnetic ordering in Fe_{1+y}Te. A spin resonance with \hbarΩ_0=6.5 meV \approx 5.3 k_BT_c and \hbarΓ=1.25 meV develops in the superconducting state from a normal state continuum. We show that the resonance is consistent with a bound state associated with s+/- superconductivity and imperfect quasi-2D Fermi surface nesting.

4 pages, 4 figures, Submitted to Phys. Rev. Lett

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Cited by in corpus (1)

• Short-range incommensurate magnetic order near the superconducting phase boundary in Fe(1+d)Te(1-x)Se(x)