We report the synthesis and characterization of polycrystalline ${\mathrm{Na}}_2{\mathrm{RuO}}_3$, a layered material in which the ${\mathrm{Ru}}^{4+}$ ($4d^4$ configuration) form a honeycomb lattice. The optimal synthesis condition was found to produce a nearly ordered ${\mathrm{Na}}_2{\mathrm{RuO}}_3$ ($C2/c$ phase), as assessed from the refinement of the time-of-flight neutron powder diffraction. Magnetic susceptibility measurements reveal a large temperature-independent Pauli paramagnetism $[{\chi }_0\sim 1.42\left(2\right)\times {10}^{-3}$ emu/mol Oe] with no evidence of magnetic ordering down to 1.5 K, and with an absence of dynamic magnetic correlations, as evidenced by neutron scattering spectroscopy. The intrinsic susceptibility (${\chi }_0$) together with the Sommerfeld coefficient of $\gamma =11.7\left(2\right)$ mJ/Ru mol ${\mathrm{K}}^2$ estimated from heat capacity measurements gives an enhanced Wilson ratio of $R_W\approx 8.9\left(1\right)$, suggesting that magnetic correlations may be present in this material. While transport measurements on pressed pellets show nonmetallic behavior, photoemission spectroscopy indicates a small but finite density of states at the Fermi energy, suggesting that the bulk material is metallic. Except for resistivity measurements, which may have been compromised by near-surface and interface effects, all other probes indicate that ${\mathrm{Na}}_2{\mathrm{RuO}}_3$ is a moderately correlated electron metal. Our results thus stand in contrast to earlier reports that ${\mathrm{Na}}_2{\mathrm{RuO}}_3$ is an antiferromagnetic insulator at low temperatures.

中文翻译：

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蜂窝状钌酸Na2RuO3的相关电子金属性能

我们报告了多晶的合成与表征 ${娜}_2{O}_3$，其中 ${茹}^{4+}$ （$4d^4$构型）形成蜂窝状晶格。发现最佳合成条件可产生几乎有序的${娜}_2{O}_3$ （$C2/C$从飞行时间中子粉末衍射的细化评估。磁化率测量表明，与温度无关的Pauli顺磁性较大$[{\chi }_0〜1.42（2）\times {10}^{-3}$emu / mol Oe]，没有证据表明低至1.5 K的磁性有序，并且没有动态磁相关，如中子散射光谱法所证明。固有磁化率（${\chi }_0$）和Sommerfeld系数 $\gamma =11.7（2）$ mJ / Ru摩尔 ${\mathrm{ķ}}^2$ 根据热容量测量结果估算，威尔逊比率提高了 ${\mathrm{[R}}_{\mathrm{w\; ^}}\approx 8.9（\mathrm{1个}）$，表明这种材料中可能存在磁相关性。尽管对压制颗粒的传输测量显示出非金属行为，但光发射光谱表明费米能量处的状态密度很小但有限，这表明块状材料是金属。除了电阻率测量值（可能已受到近地表和界面效应的影响）以外，所有其他探针均表明${娜}_2{O}_3$是一种中等相关的电子金属。因此，我们的结果与之前的报告相反${娜}_2{O}_3$ 是低温下的反铁磁绝缘体。