Nematic magnetoelastic effect contrasted betweenBa(Fe1−xCox)2As2and FeSe

Yuwen Hu, Xiao Ren, Rui Zhang, Huiqian Luo, Shigeru Kasahara, Tatsuya Watashige, Takasada Shibauchi, Pengcheng Dai, Yan Zhang, Yuji Matsuda, Yuan Li
2016 Physical review B  
To elucidate the origin of nematic order in Fe-based superconductors, we report a Raman scattering study of lattice dynamics, which quantify the extent of C_4-symmetry breaking, in BaFe_2As_2 and FeSe. FeSe possesses a nematic ordering temperature T_s and orbital-related band-energy split below T_s that are similar to those in BaFe_2As_2, but unlike BaFe_2As_2 it has no long-range magnetic order. We find that the E_g phonon-energy split in FeSe sets in only well below T_s, and its saturated
more » ... e is substantially smaller than that in BaFe_2As_2. Together with reported results for the Ba(Fe_1-xCo_x)_2As_2 family, the data suggest that magnetism exerts a major influence on the lattice.
doi:10.1103/physrevb.93.060504 fatcat:6zuh43jqjveijnfdpsuweciwhu