论文标题
来自声子光谱的软弹性常数，孔掺杂ba $ _ {1-x} $（k，na）$ _ x $ fe $ _2 $ as $ _2 $和sr $ _ {1-x} na $ _x $ _x $ _x $ _2 $ _2 $ as $ _2 $ as $ _2 $
Soft elastic constants from phonon spectroscopy in hole-doped Ba$_{1-x}$(K,Na)$_x$Fe$_2$As$_2$ and Sr$_{1-x}Na$_x$Fe$_2$As$_2$
论文作者
论文摘要
我们报告了平面偏光横向声音声子模式的非弹性X射线散射测量值，该模式沿着$ q \ parallel $ [100]在属于122个铁基超导体家族的各种孔掺杂化合物中传播。该声子模式的分散斜率与$ q \ rightArrow 0 $ limit中的剪切模量$ c_ {66} $的平方根成正比，因此，对这些化合物中发生的四方到togonal bombombombombomb的结构过渡敏感。与BA的最新报告相反（Fe $ _ {0.94} $ CO $ _ {0.06} $）$ _ 2 $ AS $ _2 $ [F。 Weber等人，物理。 Rev. B 98，014516（2018）]，我们发现从我们的实验中得出的$ C_ {66} $的定性协议与从Ba $ _ {1-x} $ _ {1-x} $（K，Na）$ _ x $ _ x $ _ x $ _2 $ _2 $ as $ _2 $ as $ _2 $ as $ _2 $ as中的Youngs Modulus中得出的价值。这些结果为最佳孔掺杂化合物的列相关长度提供了约50Å的上限。此外，我们还研究了较低的掺杂水平的化合物，这些化合物表现出正交磁相，其中$ c_ {66} $无法通过体积探针以及C4 Tetragonal磁相访问。
We report inelastic x-ray scattering measurements of the in-plane polarized transverse acoustic phonon mode propagating along $q\parallel$[100] in various hole-doped compounds belonging to the 122 family of iron-based superconductors. The slope of the dispersion of this phonon mode is proportional to the square root of the shear modulus $C_{66}$ in the $q \rightarrow 0$ limit and, hence, sensitive to the tetragonal-to-orthorhombic structural phase transition occurring in these compounds. In contrast to a recent report for Ba(Fe$_{0.94}$Co$_{0.06}$)$_2$As$_2$ [F. Weber et al., Phys. Rev. B 98, 014516 (2018)], we find qualitative agreement between values of $C_{66}$ deduced from our experiments and those derived from measurements of the Youngs modulus in Ba$_{1-x}$(K,Na)$_x$Fe$_2$As$_2$ at optimal doping. These results provide an upper limit of about 50 Å for the nematic correlation length for the optimally hole-doped compounds. Furthermore, we also studied compounds at lower doping levels exhibiting the orthorhombic magnetic phase, where $C_{66}$ is not accessible by volume probes, as well as the C4 tetragonal magnetic phase.investigated
