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研究团队通过对(La, Pr, Sm)3Ni2O7双层镍酸盐薄膜进行电输运测量，发现了伴随电子玻璃行为的时间反演对称性破缺超导电性。该超导态出现在接近零电阻态的低温区域，表现出三个显著特征：一是非常规的磁电阻回滞，这是时间反演对称性破缺的直接证据，且在不同磁场方向下均保持稳健，与涡旋钉扎或长程磁有序有本质区别；连续氧还原同时削弱了超导电性和磁滞，揭示了它们与特定镍3d电子轨道的关联。二是电流-电压响应在零场下表现出磁历史依赖性和非互易性，进一步证实了自发的内禀时间反演对称性破缺。三是移除磁场后电阻呈现对数缓慢弛豫，这是玻璃态动力学的标志。这些现象首次在镍基超导体中揭示了兼具自发时间反演对称性破缺和内在玻璃态特性的超导态，为理解高温超导机理提供了重要的现象学和概念性突破。

Layered perovskites─including the Dion–Jacobson, Ruddlesden–Popper, and Aurivillius families─exhibit a wide range of correlated electron phenomena, from high-temperature superconductivity to multiferroicity. Here, we report a new family of layered perovskites realized through topochemical oxidation of Lan+1NinO3n+1+δ (n = 1–4) Ruddlesden–Popper nickelate thin films. Postgrowth ozone annealing induces a substantial c-axis expansion─17.8% for La2NiO4+δ (n = 1)─that monotonically decreases with increasing n. Surface synchrotron X-ray diffraction and coherent Bragg rod analysis (COBRA) reveal that this structural expansion arises from the intercalation of approximately δ ≈ 0.7–1.0 oxygen atoms into interstitial sites within the rock salt spacer layers, far exceeding the previous record of δ ≈ 0.3 for any Ruddlesden–Popper oxide. These oxygen-intercalated phases form a new class of layered perovskites with a spacer layer composition intermediate between the Ruddlesden–Popper and Aurivillius phases. Furthermore, oxygen intercalation induces metallicity, enhances nickel–oxygen hybridization, and suppresses oxygen octahedral rotations, a feature associated with high-temperature superconductivity in Ruddlesden–Popper nickelates. Our work establishes topochemical oxidation as a powerful approach to accessing highly oxidized, metastable phases across a broad range of layered oxide systems, offering new platforms to engineer electronic properties via intercalation chemistry.

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Topotactical Hydrogen Induced Single-Band d -Wave Superconductivity in La₂ NiO 4

本研究利用压力-温度单晶X射线衍射与从头算密度泛函理论计算，揭示助熔剂生长的三层镍酸盐La₄Ni₃O₁₀中四方相（I4/mmm）到单斜相（P2₁/c）的转变不存在中间斜方Bmab相，而是一个直接的结构相变，并伴随两倍超结构的形成，体现为公度超晶格反射的出现。该转变温度可在14 GPa压力下从约1030 K连续抑制至20 K，说明压力有效稳定了四方相。此外，在助熔剂生长晶体中首次通过X射线衍射探测到与非公度密度波有序相关的微弱卫星反射，补充了此前仅见于浮区法晶体的结果，拉曼光谱在130 K以下观察到额外声子模式也进一步印证了该有序态。从头算计算与实验观察吻合。这项工作澄清了La₄Ni₃O₁₀结构对称性的长期争议，并支持超导电性在高压恢复四方对称性后出现，为后续电子结构及超导机理研究提供了关键的晶体学基础。

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The metal-insulator transition of La 3 Ni 2 O 7-δ with 2-dimensional electrons has been studied. Various physical properties can be understood by introducing a model of charge orderings in the NiO …