Abstract
Inelastic neutron scattering and susceptibility measurements have been performed on the optimally doped Fe-based superconductor , which has a critical temperature, of 14 K. The magnetic scattering at the stripe antiferromagnetic wave vector exhibits a “resonance” at , where the scattering intensity increases abruptly when cooled below . In a 7-T magnetic field parallel to the plane, is slightly reduced to , based on susceptibility measurements. The resonance in the neutron-scattering measurements is also affected by the field. The resonance intensity under field cooling starts to rise at a lower temperature , and the low-temperature intensity is also reduced from the zero-field value. Our results provide clear evidence for the intimate relationship between superconductivity and the resonance measured in magnetic excitations of Fe-based superconductors.
- Received 30 September 2009
DOI:https://doi.org/10.1103/PhysRevB.81.100513
©2010 American Physical Society