论文标题
对单向电荷密度波和复杂的结构调制的真实空间观察超导体BA $ _ {1-x} $ sr $ _x $ ni $ _2 $ as $ _2 $
Real-space Observation of Unidirectional Charge Density Wave and Complex Structural Modulation in the Pnictide Superconductor Ba$_{1-x}$Sr$_x$Ni$_2$As$_2$
论文作者
论文摘要
在这里，我们使用低温和可变温度的扫描隧道显微镜来研究Pnictide超导体，BA $ _ {1-x} $ sr $ _x $ ni $ _2 $ as $ _2 $。在Bani $ _2 $的低温阶段（三斜阶段）中，我们在BA和Nias表面上都观察到单向电荷密度波（CDW），$ Q $ = 1/3。在三斜bani $ _2 $的尼亚斯表面上为$ _2 $，有结构性调制引起的类似链的上层建筑，具有不同的周期性。在bani $ _2 $的高温阶段（四方阶段）中，nias表面作为周期性1 x 2上层结构出现。有趣的是，在ba $ _ {0.5} $ sr $ _ {0.5} $ ni $ _2 $ as $ _2 $的三个阶段中，单向cdw在ba/sr和nias表面上都受到抑制，而sr替换稳定在2个百分比的nias上，并稳定了2个百分比的nias，nias在nias上均增强，同时增强了nias的态度，该nias逐渐增强，这是在nias上的增强。 ba $ _ {0.5} $ sr $ _ {0.5} $ ni $ _2 $ as $ _2 $。我们的结果为单向CDW，结构调节和超导性超导率之间的相互作用提供了重要的微观见解。
Here we use low-temperature and variable-temperature scanning tunneling microscopy to study the pnictide superconductor, Ba$_{1-x}$Sr$_x$Ni$_2$As$_2$. In the low-temperature phase (triclinic phase) of BaNi$_2$As$_2$, we observe the unidirectional charge density wave (CDW) with $Q$ = 1/3 on both the Ba and NiAs surfaces. On the NiAs surface of the triclinic BaNi$_2$As$_2$, there are structural-modulation-induced chain-like superstructures with distinct periodicities. In the high-temperature phase (tetragonal phase) of BaNi$_2$As$_2$, the NiAs surface appears as the periodic 1 by 2 superstructure. Interestingly, in the triclinic phase of Ba$_{0.5}$Sr$_{0.5}$Ni$_2$As$_2$, the unidirectional CDW is suppressed on both the Ba/Sr and NiAs surfaces, and the Sr substitution stabilizes the periodic 1 by 2 superstructure on the NiAs surface, which enhance the superconductivity in Ba$_{0.5}$Sr$_{0.5}$Ni$_2$As$_2$. Our results provide important microscopic insights for the interplay among the unidirectional CDW, structural modulation, and superconductivity in this class of pnictide superconductors.
