标题： 氧同位素效应对La$_3$Ni$_2$O$_{7}$和 La$_4$Ni$_3$O$_{10}$中密度波转变的影响 显示英文标题

标题： Oxygen-isotope effect on the density wave transitions in La$_3$Ni$_2$O$_{7}$ and La$_4$Ni$_3$O$_{10}$

摘要： 固态物理学中的同位素效应对于理解原子质量如何影响材料的物理性质至关重要，并为电子-声子耦合在各种量子态形成中的作用提供了至关重要的见解。 本研究中，我们调查了氧同位素（$^{16}$O/$^{18}$O）取代对双层和三层Ruddlesden-Popper镍酸盐La$_3$Ni$_2$O$_7$和La$_4$Ni$_3$O$_{10}$中密度波转变的影响。 两种体系中的电荷密度波（CDW）转变均受到同位素取代的影响，CDW转变温度 ($T_{\rm CDW}$) 在$^{18}$氧取代的样品中向更高值移动。相比之下，自旋密度波（SDW）转变温度 ($T_{\rm SDW}$) 的同位素效应在这两个体系之间有所不同。具体而言，在La$_4$Ni$_3$O$_{10}$中，只有当CDW和SDW有序结构交织时，才观察到显著的同位素效应 ($T_{\rm SDW}$)。 这种相互作用不仅导致$T_{\rm CDW}$和$T_{\rm SDW}$的值相等，还在两种转变中产生了相同的同位素效应。相比之下，在 La$_3$Ni$_2$O$_7$中，由于 SDW 转变发生的温度与 CDW 不同，在$T_{\rm SDW}$上没有观察到同位素效应。 显示英文摘要

摘要： The isotope effect in solid-state physics is fundamental to understanding how atomic mass influences the physical properties of materials and provides crucial insights into the role of electron-phonon coupling in the formation of various quantum states. In this study, we investigate the effect of oxygen isotope ($^{16}$O/$^{18}$O) substitution on density wave transitions in the double- and triple-layer Ruddlesden-Popper nickelates La$_3$Ni$_2$O$_7$ and La$_4$Ni$_3$O$_{10}$. The charge-density wave (CDW) transitions in both systems are influenced by isotope substitution, with the CDW transition temperature ($T_{\rm CDW}$) shifting to higher values in the $^{18}$O-substituted samples. In contrast, the isotope effect on the spin-density wave (SDW) transition temperature ($T_{\rm SDW}$) differs between the two systems. Specifically, a significant isotope effect on $T_{\rm SDW}$ is observed only in La$_4$Ni$_3$O$_{10}$, where the CDW and SDW orders are intertwined. This interplay results not only in equal values for $T_{\rm CDW}$ and $T_{\rm SDW}$ but also in an identical isotope effect on both transitions. In contrast, in La$_3$Ni$_2$O$_7$, where the SDW transition occurs at a temperature distinct from the CDW, no isotope effect is observed on $T_{\rm SDW}$.