Neutron scattering is used to probe magnetic interactions as superconductivity develops in optimally doped Fe1+δSexTe1-x. Applying the first moment sum rule to comprehensive neutron scattering data, we extract the change in magnetic exchange energy Δ[JR-R′(SR·SR′)] in the superconducting state referenced to the normal state. Oscillatory changes are observed for Fe-Fe displacements |ΔR|<ξ, where ξ=1.3(1) nm is the superconducting coherence length. Dominated by a large reduction in the second nearest neighbor exchange energy [-1.2(2) meV/Fe], the overall reduction in magnetic interaction energy is Δ(Hmag)=-0.31(9) meV/Fe. Comparison to the superconducting condensation energy ΔESC=-0.013(1) meV/Fe, which we extract from specific heat data, suggests the modified magnetism we probe drives superconductivity in Fe1+δSexTe1-x.
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Sep 2 2014|
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics