We synthesized polycrystalline ${\mathrm{La}}_3{\mathrm{Ni}}_2{\mathrm{O}}_{7-\delta }$ ($\delta \approx 0.07$) samples by using the sol-gel method without postannealing under high oxygen pressure, and then measured temperature-dependent resistivity under various hydrostatic pressures up to 18 GPa by using the cubic anvil and two-stage multianvil apparatus. We find that the density-wave-like anomaly in resistivity is progressively suppressed with increasing pressure and the resistivity drop corresponding to the onset of superconductivity emerges at pressure as low as $\sim 6\mathrm{GPa}$. Zero resistivity is achieved at 9 GPa below $T_{\mathrm{c}}^{\mathrm{zero}}\approx 6.6\mathrm{K}$, which increases quickly with pressure to 41 K at 18 GPa. However, the diamagnetic response was not detected in the ac magnetic susceptibility measurements up to 15 GPa, indicating a filamentary nature of the observed superconductivity in the studied pressure range. The constructed $T\text{−}P$ phase diagram reveals an intimate relationship between superconductivity, density-wave-like order, and the strange-metal-like behaviors. The observation of zero-resistance state in the polycrystalline ${\mathrm{La}}_3{\mathrm{Ni}}_2{\mathrm{O}}_{7-\delta }$ samples under high pressures not only corroborates the recent report of superconductivity in the pressurized ${\mathrm{La}}_3{\mathrm{Ni}}_2{\mathrm{O}}_7$ crystals but also facilitates further studies on this emerging family of nickelate high-$T_{\mathrm{c}}$ superconductors.

中文翻译：

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多晶La3Ni2O7−δ 中的压力诱导超导性

我们合成了多晶${拉}_3{你}_2{\mathrm{氧}}_{7-\delta }$（$\delta \approx 0.07$）使用溶胶-凝胶法在高氧压力下不进行后退火处理样品，然后使用立方砧和两级多砧装置在高达18 GPa的各种静水压下测量温度依赖性电阻率。我们发现电阻率中的密度波状异常随着压力的增加而逐渐受到抑制，并且在压力低至以下时出现与超导性开始相对应的电阻率下降$～6\mathrm{GPa}$。在低于 9 GPa 时实现零电阻率${\mathrm{时间}}_{\mathrm{C}}^{零}\approx 6.6\mathrm{K}$，随着压力在 18 GPa 下快速增加至 41 K。然而，在高达 15 GPa 的交流磁化率测量中未检测到抗磁响应，这表明在研究的压力范围内观察到的超导性具有丝状性质。所构建的$\mathrm{时间}\text{-}磷$相图揭示了超导性、类密度波有序性和类奇怪金属行为之间的密切关系。多晶硅中零电阻状态的观察${拉}_3{你}_2{\mathrm{氧}}_{7-\delta }$高压下的样品不仅证实了最近关于加压中超导性的报道${拉}_3{你}_2{\mathrm{氧}}_7$晶体，而且还促进了对这一新兴镍酸盐高晶体家族的进一步研究${\mathrm{时间}}_{\mathrm{C}}$超导体。