Magnetoelastic coupling and charge correlation lengths in a twin domain of Ba(Fe${}_{1-x}$Co${}_x$)${}_2$As${}_2$ ($x=0.047$): A high-resolution X-ray diffraction study

Abstract

The interplay between structure, magnetism and superconductivity in single crystal Ba(Fe${}_{1-x}$Co${}_x$)${}_2$As${}_2$ (x=0.047) has been studied using high-resolution X-ray diffraction by monitoring charge Bragg reflections in each twin domain separately. The emergence of the superconducting state is correlated with the suppression of the orthorhombic distortion around \emph{T}${}_{\text{C}}$, exhibiting competition between orthorhombicity and superconductivity. Above \emph{T}${}_{\text{S}}$, the in-plane charge correlation length increases with the decrease of temperature, possibly induced by nematic fluctuations in the paramagnetic tetragonal phase. Upon cooling, anomalies in the in-plane charge correlation lengths along $a$ (${\xi }_a$) and $b$ axes (${\xi }_b$) are observed at \emph{T}${}_{\text{S}}$ and also at \emph{T}${}_{\text{N}}$ indicative of strong magnetoelastic coupling. The in-plane charge correlation lengths are found to exhibit anisotropic behavior along and perpendicular to the in-plane component of stripe-type AFM wave vector (101)${}_{\mathrm{O}}$ below around \emph{T}${}_{\text{N}}$. The temperature dependence of the out-of-plane charge correlation length shows a single anomaly at \emph{T}${}_{\text{N}}$, reflecting the connection between Fe-As distance and Fe local moment. The origin of the anisotropic in-plane charge correlation lengths ${\xi }_a$ and ${\xi }_b$ is discussed on the basis of the antiphase magnetic domains and their dynamic fluctuations.

7 pages, 6 figures, 34 references, submitted for publication in Physical Review B

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Cited by in corpus (1)

• Neutron-scattering measurements of the spin excitations in LaFeAsO and Ba(Fe${}_{0.953}$Co${}_{0.047}$)${}_2$As${}_2$: Evidence for a sharp enhancement of spin fluctuations by nematic order