发表机构
National Laboratory of Solid State Microstructures and Department of Physics, Center for Superconducting Physics and Materials, Collaborative Innovation Center of Advanced Microstructures, Nanjing University（南京大学固体微结构物理国家重点实验室、物理系、超导物理与材料中心、先进微结构协同创新中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究首次通过高温高压法合成三层Ruddlesden-Popper镍酸盐Sm₄Ni₃O₁₀₋δ，表征发现其常压下180 K处存在密度波转变，高压下未观测到超导性，为研究该类镍酸盐基础物理提供了新平台。
AI 中文摘要
Ruddlesden-Popper（RP）镍酸盐中高温超导电性的发现已引起广泛关注。在压力下，三层镍酸盐La₄Ni₃O₁₀₋δ（T_c≈30 K）和Pr₄Ni₃O₁₀₋δ（T_c≈40.5 K）会出现体超导电性，其中Pr³+的离子半径较小，可能产生内部化学压力并提高T_c。然而，合成含更小稀土元素（Ln）的三层RP相极具挑战性，目前仅合成了La、Pr、Nd的类似物，且为单一稀土形式的稳定相。本研究首次通过高温高压（HPHT）方法成功合成了钐基化合物Sm₄Ni₃O₁₀₋δ。磁化率和输运测量一致证实，该化合物在常压下于~180 K处存在密度波（DW）转变。通过对Sm₄Ni₃O₁₀₋δ结构数据的仔细拟合发现，与层间顶端氧相关的Ni-O-Ni键角远小于180°，而180°曾被认为是超导电性出现的关键因素。在施加高达80 GPa的压力后，尽管绝缘行为和DW序被部分抑制，但本研究未观测到超导电性。密度泛函理论计算表明，3d_z²和3d_x²-y²轨道与其他t₂g轨道分离，对费米面起主要贡献。新合成的三层镍酸盐Sm₄Ni₃O₁₀₋δ为探索RP镍酸盐的基础物理提供了独特平台。
英文摘要
The discovery of high-temperature superconductivity in Ruddlesden-Popper (RP) nickelates has attracted significant attention. Bulk superconductivity emerges under pressure in trilayer nickelates La$_4$Ni$_3$O$_{10-δ}$ (T$_c$ $\approx$ 30 K) and Pr$_4$Ni$_3$O$_{10-δ}$ (T$_c$ $\approx$ 40.5 K), where the reduced ionic radius of Pr$^{3+}$ may generate internal chemical pressure and enhance T$_c$. However, synthesizing trilayer RP phases with smaller rare-earth elements (Ln) is extremely challenging. So far, only the La, Pr, and Nd analogues have been synthesized with stable phases in the single rare-earth form. Here we report the first successful high-pressure and high-temperature (HPHT) synthesis of samarium-based compound Sm$_4$Ni$_3$O$_{10-δ}$. Magnetization and transport measurements consistently confirm a density wave (DW) transition at ~180 K at ambient pressure. Through a careful fitting to the structural data of Sm$_4$Ni$_3$O$_{10-δ}$, it is found that the bond angle of (Ni-O-Ni) associating with the interlayer apical oxygen is much smaller than 180$^{\circ}$, which was assumed to be the key factor for the occurrence of superconductivity. By applying pressures up to 80 GPa, despite partial suppression of insulating behavior and the DW order, but superconductivity is not observed in our present study. Density functional theory calculations suggest that the 3d$_{z^2}$ and 3d$_{x^2-y^2}$ are separated from other t$_{2g}$ orbitals and make a primary contribution to the Fermi surface. The newly synthesized trilayer nickelate Sm$_4$Ni$_3$O$_{10-δ}$ offers a unique platform for probing the fundamental physics of RP nickelates.
Comments21 pages, 4 figures
Journal refMaterials Today Physics 60 (2026) 102005
DOI：10.1016/j.mtphys.2025.102005
