Abstract
The interplay between structure, magnetism, and superconductivity in single crystal Ba(FeCo)As () 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 , exhibiting competition between orthorhombicity and superconductivity. Above , 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 () and axes () are observed at and also at 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) below around . The temperature dependence of the out-of-plane charge correlation length shows a single anomaly at , reflecting the connection between Fe-As distance and Fe local moment. The origin of the anisotropic in-plane charge correlation lengths and is discussed on the basis of the antiphase magnetic domains and their dynamic fluctuations.
- Received 16 February 2013
DOI:https://doi.org/10.1103/PhysRevB.87.094510
©2013 American Physical Society