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arXiv · 1712.01903

Anomalous magneto-elastic coupling in Au-doped BaFe2As2

S. -F. Wu·W. -L. Zhang·L. Li·H. -B. Cao·H. -H. Kung·A. S. Sefat·H. Ding·P. Richard·G. Blumberg
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Abstract

We used polarization-resolved Raman scattering to study magneto-elastic coupling in Ba(Fe$_{1-x}$Au$_{x}$)$_2$As$_2$ crystals as a function of light Au-doping, materials for which temperatures of the structural transition ($T_S$) and of the magnetic ordering transition ($T_N$) split. We study the appearance of the $A_g$(As)phonon intensity in the $XY$ scattering geometry that is very weak just below $T_S$, but for which the intensity is significantly enhanced below $T_N$. In addition, the $A_g$(As) phonon shows an asymmetric line shape below $T_N$ and an anomalous linewidth broadening upon Au-doping in the magnetic phase. We demonstrate that the anomalous behavior of the $A_g$(As) phonon mode in the $XY$ scattering geometry can be consistently described by a Fano model involving the $A_g$(As) phonon mode interacting with the $B_{2g}$ symmetry-like magnetic continuum in which the magneto-elastic coupling constant is proportional to the magnetic order parameter.

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S. -F. Wu, W. -L. Zhang, L. Li, H. -B. Cao, H. -H. Kung, A. S. Sefat, H. Ding, P. Richard, G. Blumberg. 2017-12-05. Anomalous magneto-elastic coupling in Au-doped BaFe2As2. https://doi.org/10.1103/physrevb.102.014501

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