Abstract
We use inelastic neutron scattering to study energy and wave vector dependence of spin fluctuations in , derived from iron pnictide superconductors. Our data reveal the coexistence of antiferromagnetic (AF) and ferromagnetic (FM) spin fluctuations at wave vectors and , respectively. By comparing neutron scattering results with those of dynamic mean field theory calculation and angle-resolved photoemission spectroscopy experiments, we conclude that both AF and FM spin fluctuations in are closely associated with a flatband of the orbitals near the Fermi level, different from the orbitals in superconducting . Therefore, Co substitution in induces a to orbital switching, and is responsible for FM spin fluctuations detrimental to the singlet pairing superconductivity.
- Received 8 August 2018
DOI:https://doi.org/10.1103/PhysRevLett.122.117204
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