论文标题
在BA（NI，CO）$ _ 2 $（as，p）$ _ 2 $的旋转对称性破裂，在不符合的电荷密度波转换下
Rotational symmetry breaking at the incommensurate charge-density-wave transition in Ba(Ni,Co)$_2$(As,P)$_2$: Possible nematic phase induced by charge/orbital fluctuations
论文作者
论文摘要
高温超导体中的列型相变对这些系统的电子特性具有很大的影响。 Bafe $ _2 $ AS $ _2 $，\@@ nematic过渡在137 k左右，由磁波动引起，bani $ _2 $ as $ _2 $，\@ a bafe $ _2 $ as $ _2 $ as $ _2 $具有在同一温度范围内的结构过渡，\@ $ i4/mmm $。\@@@与bafe $ _2 $作为$ _2 $相反，在某些情况下，在正骨bombic low-t $ phase中找到了分线条纹磁性订单，这是一个单向电荷密度的密度波和（扭曲的）zig-zag链条的triclinic low-$ t $ the $ the $ the $ _2 $ _2 $ _2 $ _2 $ _2 $ _2 $。 BA（NI，CO）的高和低$ T $阶段$ _ 2 $（AS，P）$ _ 2 $一个额外的阶段，带有损坏的四倍对称性和$ d_ {xz} $ orbital Order，这是充电/Orbital-Fluctital-Fluctitual-Fluctiation-Fluctiation-fluctiation-fluctiation-fluctucation-tocucation-tocucation-fluctation-fluctiation-fluctiation-fluctiation-fluctiation-fluctiation-fluctiation-fluctation-tocucation-nematicality。此外，我们的数据表明，为BA（Ni，Co）$ _ 2 $（as，p）$ _ 2 $找到的增强$ T _ {\ rm c} $用于更高的CO或P替代级别可能是由于抑制（变形的）Zig-Zag链减少$ D_ {XY $ orbitals的贡献而导致的。
Nematic phase transitions in high-temperature superconductors have a strong impact on the electronic properties of these systems. BaFe$_2$As$_2$,\@ with an established nematic transition around 137 K induced by magnetic fluctuations, and BaNi$_2$As$_2$,\@ a non-magnetic analog of BaFe$_2$As$_2$ with a structural transition in the same temperature range,\@ share a common tetragonal aristotype crystal structure with space-group type $I4/mmm$.\@ In contrast to BaFe$_2$As$_2$ where collinear stripe magnetic order is found for the orthorhombic low-$T$ phase, a unidirectional charge density wave together with (distorted) zig-zag chains are observed for the triclinic low-$T$ phase of BaNi$_2$As$_2$.\@ Here we show that between the high- and low-$T$ phases of Ba(Ni,Co)$_2$(As,P)$_2$ an additional phase with broken fourfold symmetry and $d_{xz}$ orbital order exists which is a promising candidate for charge/orbital-fluctuation-induced nematicity. Moreover, our data suggest that the enhanced $T_{\rm c}$ found for Ba(Ni,Co)$_2$(As,P)$_2$ for higher Co or P substitution levels might result from suppression of the (distorted) zig-zag chains by reducing the contribution of the $d_{xy}$ orbitals.
