We investigate in detail the low-temperature structural and physical properties of the trilayer nickelates $R_4{\mathrm{Ni}}_3{\mathrm{O}}_{10}$ ($R=\mathrm{La}$, Pr, and Nd), which crystallize with a monoclinic symmetry (space group $P{2}_{1}a,Z=4$) and undergo a metal-to-metal transition (MMT) near $T_{\mathrm{MMT}}$= $135\mathrm{K}\left(\mathrm{La}\right), 156\mathrm{K}$ (Pr), and $160\mathrm{K}$ (Nd). Using a high-resolution synchrotron powder x-ray diffraction technique, we show that the lattice parameters in all cases exhibit an anomalous behavior at $T_{\mathrm{MMT}}$, however, without any sign of change in the lattice symmetry. Unambiguous signature of MMT is also observed in the magnetic and transport data, suggesting a strong coupling between the electronic, magnetic, and structural degrees of freedom. Analysis of thermal expansion yields hydrostatic pressure dependence of MMT in close agreement with previous high-pressure experiments. In ${\mathrm{Pr}}_4{\mathrm{Ni}}_3{\mathrm{O}}_{10}$, the ${\mathrm{Pr}}^{3+}$ ions located in the rocksalt (RS) layers order magnetically near $5\mathrm{K}$, which is significantly suppressed compared to ${\theta }_p\sim -36\mathrm{K}$. In contrast, ${\mathrm{Pr}}^{3+}$ ions in the perovskite-block (PB) layers exhibit a crystal field (CF) induced nonmagnetic singlet ground state. In ${\mathrm{Nd}}_4{\mathrm{Ni}}_3{\mathrm{O}}_{10}$, on the other hand, the CF ground state of ${\mathrm{Nd}}^{3+}$ ions in both RS and PB layers is a Kramers doublet. The heat capacity of ${\mathrm{Nd}}_4{\mathrm{Ni}}_3{\mathrm{O}}_{10}$ shows a pronounced Schottky-like anomaly near $40\mathrm{K}$, and a sharp upturn indicating short-range correlations between the Nd-moments below $10\mathrm{K}$. However, no signs of long-range ordering of Nd-moments could be found down to $2\mathrm{K}$ despite a sizable value of ${\theta }_p\sim -40\mathrm{K}$. The strongly suppressed magnetic long-range ordering in both $R=\mathrm{Pr}$ and Nd suggests the presence of strong magnetic frustration in these compounds. In the presence of an overwhelming Schottky contribution, the electronic term in the specific heat of ${\mathrm{Pr}}_4{\mathrm{Ni}}_3{\mathrm{O}}_{10}$ and ${\mathrm{Nd}}_4{\mathrm{Ni}}_3{\mathrm{O}}_{10}$ appears highly inflated, which can be falsely interpreted as a sign of heavy fermion behavior as is done in a recent study on ${\mathrm{Nd}}_4{\mathrm{Ni}}_3{\mathrm{O}}_{10}$. Accordingly, the low-temperature resistivity of these compounds is found to follow a $-T^{0.5}$ rather than a $-\ln T$ dependence.

中文翻译：

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三层镍酸盐的结构和物理性质R4Ni3O10（R = La，Pr和Nd）

我们详细研究了三层镍酸盐的低温结构和物理性质 ${\mathrm{[R}}_4{你}_3{\mathrm{Ø}}_{10}$ （$\mathrm{[R}=啦$，Pr和Nd），它们以单斜晶对称性结晶（空间群 $P{2}_{\mathrm{1个}}\mathrm{一种}，ž=4$）并在附近进行金属到金属的过渡（MMT） ${Ť}_{\mathrm{MMT}}$= $135\mathrm{ķ}（啦）， 156\mathrm{ķ}$ （Pr），以及 $160\mathrm{ķ}$（Nd）。使用高分辨率同步加速器粉末X射线衍射技术，我们显示了在所有情况下的晶格参数均表现出异常行为。${Ť}_{\mathrm{MMT}}$但是，晶格对称性没有任何变化的迹象。在磁数据和传输数据中也观察到MMT的明确签名，这表明电子，磁和结构自由度之间存在强耦合。热膨胀分析产生MMT的静水压力依赖性，与先前的高压实验非常吻合。在${镨}_4{你}_3{\mathrm{Ø}}_{10}$， ${镨}^{3+}$ 位于岩盐（RS）层中的离子在附近具有磁性排序 $5\mathrm{ķ}$，与 ${\theta }_p〜-36\mathrm{ķ}$。相反，${镨}^{3+}$钙钛矿块（PB）层中的离子显示出晶场（CF）诱导的非磁性单线态基态。在${钕}_4{你}_3{\mathrm{Ø}}_{10}$另一方面，CF的基态 ${钕}^{3+}$RS和PB层中的离子均为Kramers双峰。热容量${钕}_4{你}_3{\mathrm{Ø}}_{10}$ 在附近显示出明显的类似于肖特基的异常 $40\mathrm{ķ}$，并且急剧上升表明下面的Nd矩之间存在短时相关性 $10\mathrm{ķ}$。但是，直到Nd矩都没有发现长期有序的迹象。$2\mathrm{ķ}$ 尽管价值可观 ${\theta }_p〜-40\mathrm{ķ}$。两者中的强抑制磁远距离有序$\mathrm{[R}=镨$Nd表示这些化合物中存在强烈的磁阻。在压倒性的肖特基贡献存在的情况下，${镨}_4{你}_3{\mathrm{Ø}}_{10}$ 和 ${钕}_4{你}_3{\mathrm{Ø}}_{10}$似乎高度膨胀，这可以被错误地解释为费米子行为严重的迹象，就像最近对${钕}_4{你}_3{\mathrm{Ø}}_{10}$。因此，发现这些化合物的低温电阻率遵循$-{Ť}^{0.5}$ 而不是 $-\ln Ť$ 依赖。