The discovery of superconductivity in a $d^{9-\delta }$ nickelate has inspired disparate theoretical perspectives regarding the essential physics of this class of materials. A key issue is the magnitude of the magnetic superexchange, which relates to whether cuprate-like high-temperature nickelate superconductivity could be realized. We address this question using Ni $L$-edge and O $K$-edge spectroscopy of the reduced $d^{9-1/3}$ trilayer nickelates $R_4{\mathrm{Ni}}_3{\mathrm{O}}_8$ (where $R=\mathrm{La}$, Pr) and associated theoretical modeling. A magnon energy scale of $\sim 80\mathrm{meV}$ resulting from a nearest-neighbor magnetic exchange of $J=69(4)\mathrm{meV}$ is observed, proving that $d^{9-\delta }$ nickelates can host a large superexchange. This value, along with that of the Ni-O hybridization estimated from our O $K$-edge data, implies that trilayer nickelates represent an intermediate case between the infinite-layer nickelates and the cuprates. Layered nickelates thus provide a route to testing the relevance of superexchange to nickelate superconductivity.

中文翻译：

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共振非弹性X射线散射揭示ad9-δ镍酸盐中的强超交换

超导的发现 $d^{9-\delta }$镍酸盐激发了有关此类材料本质物理学的不同理论观点。关键问题是磁性超交换的大小，这与能否实现类似铜酸盐的高温镍酸盐超导性有关。我们使用镍解决这个问题$\mathrm{大号}$边和O $ķ$还原的前沿光谱 $d^{9-\mathrm{1个}/3}$ 三层镍酸盐 ${\mathrm{[R}}_4{你}_3{\mathrm{Ø}}_8$ （在哪里 $\mathrm{[R}=啦$，Pr）和相关的理论模型。磁能级$〜80\mathrm{病毒}$ 由最近邻磁交换产生的 $Ĵ=69（4）\mathrm{病毒}$ 被观察到，证明 $d^{9-\delta }$镍酸盐可以容纳大型超级交换。该值以及根据我们的O估计的Ni-O杂交的值$ķ$-边缘数据暗示三层镍酸盐代表无限层镍酸盐和铜酸盐之间的中间情况。层状镍酸盐因此提供了测试超交换与镍酸盐超导性相关性的途径。