Spin gap and resonance at the nesting wave vector in superconducting FeSe0.4Te0.6

Embargo until
Date
2009-08-07
Journal Title
Journal ISSN
Volume Title
Publisher
American Physical Society
Abstract
Neutron scattering is used to probe magnetic excitations in FeSe0.4Te0.6 (Tc = 14 K). Low energy spin fluctuations are found with a characteristic wave vector (1212L) that corresponds to Fermi surface nesting and differs from Qm = (δ012) for magnetic ordering in Fe1+yTe. A spin resonance with ℎΩ0 = 6.51(4) meV ≈ 5.3kBTc and ℎΓ = 1.25(5) 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.
Description
Keywords
spin resonance, spin gap, nesting wave vector, tellurium alloys, selenium alloys, probe magnetic excitations, low energy spin fluctuations, magnetic ordering, normal state continuum, neutron diffraction, iron alloys, Fermi surface, bound states, imperfect quasi 2D Fermi surface nesting, superconductivity, FeSe0.4Te0.6Jk
Citation
Source: Physical Review Letters 7 Aug. 2009, vol.103, no.6, 067008 (4 pp.