Condensed Matter (Jul 2019)
<b>Q</b> Dependence of Magnetic Resonance Mode on FeTe<sub>0.5</sub>Se<sub>0.5</sub> Studied by Inelastic Neutron Scattering
Abstract
Inelastic neutron scattering measurements have been performed on a superconducting single crystal FeTe 0.5 Se 0.5 to examine the Q -dependent enhancement of the dynamical structure factor, S ( Q , E ) , from Q = (0, 0) to ( π , π ), including ( π , 0) in the superconducting state. In most of iron-based superconductors, S ( Q , E ) is enhanced at Q = ( π , 0), where the “magnetic resonance mode” is commonly observed in the unfolded Brillouin zone. Constant-E cuts of S ( Q , E ) suggest that the enhancement is not uniform in the magnetic excitation, and limited around Q = ( π , 0). This result is consistent with the theoretical simulation of the magnetic resonance mode due to the Bardeen−Cooper−Schrieffer coherence factor with the sign-reversing order parameter of s ± wave.
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