- By:
- Li, Yu; Yin, Zhiping; Wang, Weiyi; Xu, Zhuang; Song, Yu; Tian, Long; Shen, Dawei; Abernathy, Douglas L; Niedziela, Jennifer L; Ewings, Russell; Perring, T.; Pajerowski, Daniel M; Matsuda, Masaaki ; Bourges, Philippe; Mechthild, Enderle; Su, Yixi; Dai, Pengcheng; Liu, Zhonghao; Huang, Yaobo
- Journal Name:
- Physical Review Letters
- Page Number:
- 117204
- Volume:
- 122
- Issue Number:
- 11
- Publication Date:
- April 24, 2019
- View DOI Listing:
- https://doi.org/10.1103/PhysRevLett.122.117204
Abstract
We use inelastic neutron scattering to study energy and wave vector dependence of spin fluctuations in SrCo2As2, derived from SrFe2−xCoxAs2 iron pnictide superconductors. Our data reveal the coexistence of antiferromagnetic (AF) and ferromagnetic (FM) spin fluctuations at wave vectors QAF=(1,0) and QFM=(0,0)/(2,0), 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 SrCo2As2 are closely associated with a flatband of the eg orbitals near the Fermi level, different from the t2g orbitals in superconducting SrFe2−xCoxAs2. Therefore, Co substitution in SrFe2−xCoxAs2 induces a t2g to eg orbital switching, and is responsible for FM spin fluctuations detrimental to the singlet pairing superconductivity.
