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arXiv · 1510.03526

Nematic magnetoelastic effect contrasted between Ba(Fe$_{1-x}$Co$_{x}$)$_2$As$_2$ and FeSe

Yuwen Hu·Xiao Ren·Rui Zhang·Huiqian Luo·Shigeru Kasahara·Tatsuya Watashige·Takasada Shibauchi·Pengcheng Dai·Yan Zhang·Yuji Matsuda·Yuan Li
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Abstract

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$_2$As$_2$ and FeSe. FeSe possesses a nematic ordering temperature $T_\mathrm{s}$ and orbital-related band-energy split below $T_\mathrm{s}$ that are similar to those in BaFe$_2$As$_2$, but unlike BaFe$_2$As$_2$ it has no long-range magnetic order. We find that the $E_g$ phonon-energy split in FeSe sets in only well below $T_\mathrm{s}$, and its saturated value is substantially smaller than that in BaFe$_2$As$_2$. Together with reported results for the Ba(Fe$_{1-x}$Co$_{x}$)$_2$As$_2$ family, the data suggest that magnetism exerts a major influence on the lattice.

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Yuwen Hu, Xiao Ren, Rui Zhang, Huiqian Luo, Shigeru Kasahara, Tatsuya Watashige, Takasada Shibauchi, Pengcheng Dai, Yan Zhang, Yuji Matsuda, Yuan Li. 2015-10-13. Nematic magnetoelastic effect contrasted between Ba(Fe$_{1-x}$Co$_{x}$)$_2$As$_2$ and FeSe. https://doi.org/10.1103/physrevb.93.060504

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