标题： 高温无限层镍酸盐超导体中的持久态磁子 显示英文标题

标题： Persistent paramagnons in high-temperature infinite-layer nickelate superconductors

摘要： 最近在空穴掺杂的SmNiO$_2$中发现高温超导性，其转变温度$T_c$是无限层（IL）镍氧化物中的最高记录，这为探索超导性的设计原理开辟了新途径。实验确定这种新体系中的电子结构和磁相互作用对于阐明增强超导性的机制至关重要。 这里，我们报告了对基于钐的超导IL镍氧化物薄膜的Ni$L$边缘共振非弹性X射线散射（RIXS）研究。Sm$_{1-x-y-z}$Eu$_x$Ca$_y$Sr$_z$NiO$_2$ (SECS)。在最佳掺杂和过掺杂的SECS样品中观察到了色散的磁涨落激发，支持自旋涨落介导的配对机制。 然而，尽管在Sm基镍酸盐中$T_c$的两倍增强，与它们的Pr基对应物相比，有效交换耦合强度减少了大约$20\%$。这种行为与空穴掺杂的铜氧化物不同，其中磁相互作用与$T_c$正相关，突显了它们超导机制的重要差异。 显示英文摘要

摘要： The recent discovery of high-temperature superconductivity in hole-doped SmNiO$_2$, exhibiting the record-high transition temperature $T_c$ among infinite-layer (IL) nickelates, has opened a new avenue for exploring design principles of superconductivity. Experimentally determining the electronic structure and magnetic interactions in this new system is crucial to elucidating the mechanism behind the enhanced superconductivity. Here, we report a Ni $L$-edge resonant inelastic x-ray scattering (RIXS) study of superconducting Sm-based IL nickelate thin films Sm$_{1-x-y-z}$Eu$_x$Ca$_y$Sr$_z$NiO$_2$ (SECS). Dispersive paramagnonic excitations are observed in both optimally and overdoped SECS samples, supporting a spin-fluctuation-mediated pairing scenario. However, despite the two-fold enhancement of $T_c$ in the Sm-based nickelates compared to their Pr-based counterparts, the effective exchange coupling strength is reduced by approximately $20\%$. This behavior contrasts with hole-doped cuprates, where magnetic interactions correlate positively with $T_c$, highlighting essential differences in their superconducting mechanisms.