La₂SmNi₂O₇中无位移电荷密度波的压力驱动结构转变
Pressure-Driven Structural Transitions without a Displacive Charge-Density Wave in La$_2$SmNi$_2$O$_7$
AI总结：
研究双层镍酸盐La₂SmNi₂O₇结构特性随压力和温度的变化，通过实验观察到压力诱导的结构转变，超导穹顶内高质量X射线衍射数据助于理解超导性。
摘要：
我们研究了双层镍酸盐La₂SmNi₂O₇的结构特性随压力和温度的变化。在环境条件下，该材料结晶为单斜超结构。低温下未检测到与电荷密度波（CDW）有序相关的卫星反射。压缩时观察到从单斜到正交再到四方的压力诱导结构转变。超导穹顶内的X射线衍射数据有助于理解超导性的出现。
英文摘要：
We investigated the structural properties of bilayer nickelate La$_2$SmNi$_2$O$_7$ as a function of pressure and temperature. At ambient conditions, we show that the material crystallizes as a monoclinic superstructure distinct from the one previously reported and close to the pseudo-orthorhombic structure of pristine La$_3$Ni$_2$O$_7$. No signatures of satellite reflections associated with charge density wave (CDW) ordering are detected at low temperature. Upon compression, a sequence of pressure-induced structural transitions from monoclinic to orthorhombic 15 GPa and then tetragonal 21 GPa symmetry is observed. Within the superconducting dome, the quality of the X-ray diffraction data enables structural refinements enabling theoretical models to understand the emergence of superconductivity.
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