Two-magnon Raman scattering inA0.8Fe1.6Se2systems (A=K, Rb, Cs, and Tl): Competition between superconductivity and antiferromagnetic order

A. M. Zhang, J. H. Xiao, Y. S. Li, J. B. He, D. M. Wang, G. F. Chen, B. Normand, Q. M. Zhang, T. Xiang
2012 Physical Review B  
We have performed Raman-scattering measurements on high-quality single crystals of A_0.8Fe_1.6Se_2 superconductors of several compositions. We find a broad, asymmetric peak around 1600 cm^-1 (200 meV), which we identify as a two-magnon process involving optical magnons. The intensity of the two-magnon peak falls sharply on entering the superconducting phase. This effect, which is entirely absent in the non-superconducting system KFe_1.5Se_2, requires a strong mutual exclusion between
more » ... gnetism and superconductivity arising from proximity effects within regions of microscale phase separation.
doi:10.1103/physrevb.85.214508 fatcat:dnyffoxmcfbfpb3tepiqaw2xwq