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无限层镍氧化物Nd0.8Sr0.2NiO2薄膜中超导电性的发现, 建立了另一类非常规超导体, 其结构和电子配对方式和铜氧化物超导体类似. 不同于铜氧化物超导体的是, 无限层镍氧化物仅在薄膜样品中观察到了超导性, 其中界面结构、元素掺杂和无限层结构等因素是理解薄膜超导机制的关键. 因此, 薄膜与衬底之间的界面效应对超导机制的影响值得我们探究, 然而目前对超导和非超导的镍氧化物Nd0.8Sr0.2NiOx薄膜界面结构的对比研究还没有报道过. 本文基于扫描透射电镜技术, 以Nd0.8Sr0.2NiO3/SrTiO3和Nd0.8Sr0.2NiO2/SrTiO3为主要研究对象, 探究了镍氧化物Nd0.8Sr0.2NiOx薄膜在还原前后相分布和界面结构产生的变化, 观测到界面处元素混合、原子台阶以及晶格常数变化等现象, 同时发现了镍氧化物Nd0.8Sr0.2NiO2薄膜在靠近界面处1—2层单胞内未被完全还原成超导无限层结构. 本研究强调了镍氧化物Nd0.8Sr0.2NiOx薄膜与衬底之间界面的原子重构及调制作用, 为无限层镍基薄膜超导结构的研究提供了帮助.
The discovery of superconductivity in infinite-layer nickelate Nd0.8Sr0.2NiO2 has established another type of unconventional superconductors, whose structure and electron pairing mechanism are similar to those of cuprate superconductors. Unlike in cuprate superconductors, superconductivity in infinite-layer nickelates has only been observed in thin film samples, where heterointerface structures, elemental doping, and the infinite-layer configuration are critical for epitaxial systems. Therefore, the film-substrate interfacial effects require exploration for understanding superconductivity. However, comparative studies on the interfacial structures between superconducting and non-superconducting Nd0.8Sr0.2NiOx nickelate thin films have not been reported in the literature so far. This work focuses on Nd0.8Sr0.2NiO3/SrTiO3 and Nd0.8Sr0.2NiO2/SrTiO3, and the phase distribution and interfacial structural changes in superconducting and non-superconducting nickelate thin films are characterized in detail by using scanning transmission electron microscopy (STEM). Further analysis of the corresponding atomic HAADF, iDPC images and EDS maps reveals the phenomena such as elements mixing, atomic steps, and changes in lattice parameters at the interfaces. These results also show that in the Nd0.8Sr0.2NiO2 film, the first 1—2 unit cells near the interface are not fully reduced to the superconducting infinite-layer structure. Such findings contribute to alleviating the strong polarity discontinuity at the sharp interface. This study also emphasizes the atomic reconstruction and the modulation effect at the interface between the substrate and the film, thus enriching the understanding of the structural properties of the Nd0.8Sr0.2NiOx films, and providing crucial experimental evidence for understanding the interfacial structure of infinite-layer nickelates. -
图 1 (a), (b) Nd0.8Sr0.2NiO3/SrTiO3原子模型图及对应的HAADF图像; (c), (d) Nd0.8Sr0.2NiO2/SrTiO3原子模型图及对应的HAADF图像; (e) Nd0.8Sr0.2NiO2/SrTiO3, Nd0.8Sr0.2NiO3/SrTiO3的电阻率随温度的变化; (f), (g) 分别为Nd0.8Sr0.2NiO2/SrTiO3, Nd0.8Sr0.2NiO3/SrTiO3的几何相位图, 黄框标记的为RP相区域
Fig. 1. (a), (b) Atomic structure model and HAADF image of the Nd0.8Sr0.2NiO3/SrTiO3; (c), (d) the atomic structure model and HAADF image of the Nd0.8Sr0.2NiO2/SrTiO3; (e) the temperature-dependent resistivity profile of Nd0.8Sr0.2NiO2/SrTiO3 and Nd0.8Sr0.2NiO3/SrTiO3; (f), (g) the geometric phase analysis of Nd0.8Sr0.2NiO2/SrTiO3 and Nd0.8Sr0.2NiO3/SrTiO3, the RP phase regions marked by yellow boxes.
图 2 (a) Nd0.8Sr0.2NiO3/STO界面[100]取向的HAADF图像及相应的EDS分布图; (b) 图(a)对应的EDS积分强度分析图; (c) Nd0.8Sr0.2NiO2/STO界面[100]取向HAADF图像及相应的EDS分布图; (d) 图(c)对应的EDS积分强度分析图
Fig. 2. (a) HAADF image at [100] orientation of the Nd0.8Sr0.2NiO3/STO interface and corresponding EDS mapping images; (b) the EDS integrated line intensity analysis corresponding to panel (a); (c) the HAADF image at [100] orientation of the Nd0.8Sr0.2NiO2/STO interface and corresponding EDS mapping images; (d) the EDS intensity analysis corresponding to panel (c).
图 3 (a) Nd0.8Sr0.2NiO3/SrTiO3沿[100]方向HAADF和iDPC图像; (b) Nd0.8Sr0.2NiO2/SrTiO3沿[100]方向HAADF和iDPC图像; (c) Nd0.8Sr0.2NiO2/SrTiO3界面处原子台阶HAADF图像; (d) Nd0.8Sr0.2NiO2/SrTiO3界面处面内a和面外c晶格常数在空间上的变化; (e) 1, 2, 3三个区域对应的放大iDPC图和原子模型图
Fig. 3. (a) HAADF and iDPC images in the direction of [100] of the Nd0.8Sr0.2NiO3/SrTiO3; (b) HAADF and iDPC images in the direction of [100] of the Nd0.8Sr0.2NiO2/SrTiO3; (c) HAADF image of atomic steps appear at the Nd0.8Sr0.2NiO2/SrTiO3 interface; (d) spatial variation of the in-plane (a) and out-of-plane (c) lattice parameters across the Nd0.8Sr0.2NiO2/SrTiO3; (e) the magnified iDPC images and structure model corresponding to regions 1, 2 and 3.
图 4 (a), (c) Nd0.8Sr0.2NiO3/SrTiO3, Nd0.8Sr0.2NiO2/SrTiO3薄膜沿[100]带轴的HAADF图像; (b), (d) Nd0.8Sr0.2NiO3/SrTiO3, Nd0.8Sr0.2NiO2/SrTiO3沿面内和面外方向的晶格常数随位置的变化
Fig. 4. (a), (c) HAADF images of the Nd0.8Sr0.2NiO3/SrTiO3 and Nd0.8Sr0.2NiO2/SrTiO3 films along the [100] axis; (b), (d) variation of the lattice constants along the in-plane and out-of-plane directions as a function of position for Nd0.8Sr0.2NiO3/SrTiO3 and Nd0.8Sr0.2NiO2/SrTiO3 films.
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[1] Gu Q Q, Li Y Y, Wan S Y, Li H Z, Guo W, Yang H, Li Q, Zhu X Y, Pan X Q, Nie Y F, Wen H H 2020 Nat. Commun. 11 6027
Google Scholar
[2] Hepting M, Li D, Jia C J, Lu H, Paris E, Tseng Y, Feng X, Osada M, Been E, Hikita Y, Chuang Y D, Hussain Z, Zhou K J, Nag A, Garcia Fernandez M, Rossi M, Huang H Y, Huang D J, Shen Z X, Schmitt T, Hwang H Y, Moritz B, Zaanen J, Devereaux T P, Lee W S 2020 Nat. Mater. 19 381
Google Scholar
[3] Goodge B H, Geisler B, Lee K, Osada M, Wang B Y, Li D F, Hwang H Y, Pentcheva R, Kourkoutis L F 2023 Nat. Mater. 22 466
Google Scholar
[4] Anisimov V I, Bukhvalov D, Rice T M 1999 Phys. Rev. B 59 7901
Google Scholar
[5] Crespin M, Levitz P, Gatineau L 1983 J. Chem. Soc. , Faraday Trans. 79 1181
Google Scholar
[6] Hayward M A, Green M A, Rosseinsky M J, Sloan J 1999 J. Am. Chem. Soc. 121 8843
Google Scholar
[7] Li D F, Lee K, Wang B Y, Osada M, Crossley S, Lee H R, Cui Y, Hikita Y, Hwang H Y 2019 Nature 572 624
Google Scholar
[8] Li D F, Wang B Y, Lee K, Harvey S P, Osada M, Goodge B H, Kourkoutis L F, Hwang H Y 2020 Phys. Rev. Lett. 125 027001
Google Scholar
[9] Puphal P, Wu Y M, Fürsich K, Lee H, Pakdaman M, Bruin J A N, Nuss J, Suyolcu Y E, van Aken P A, Keimer B, Isobe M, Hepting M 2021 Sci. Adv. 7 eabl8091
Google Scholar
[10] Parzyck C T, Gupta N K, Wu Y, Anil V, Bhatt L, Bouliane M, Gong R, Gregory B Z, Luo A, Sutarto R, He F, Chuang Y D, Zhou T, Herranz G, Kourkoutis L F, Singer A, Schlom D G, Hawthorn D G, Shen K M 2024 Nat. Mater. 23 486
Google Scholar
[11] Li Q, He C P, Si J, Zhu X Y, Zhang Y, Wen H H 2020 Commun. Mater. 1 16
Google Scholar
[12] Wang B X, Zheng H, Krivyakina E, Chmaissem O, Lopes P P, Lynn J W, Gallington L C, Ren Y, Rosenkranz S, Mitchell J F 2020 Phys. Rev. Mater. 4 084409
Google Scholar
[13] Lee Y, Wei X, Yu Y J, Bhatt L, Lee K, Goodge B H, Harvey S P, Wang B Y, Muller D A, Kourkoutis L F, Lee W S, Raghu S, Hwang H Y 2025 Nat. Synth. DOI: 10.1038/s44160-024-00714-2
[14] Sun H L, Huo M W, Hu X W, Li J Y, Liu Z J, Han Y F, Tang L Y, Mao Z Q, Yang P T, Wang B S 2023 Nature 621 493
Google Scholar
[15] Ko E K, Yu Y J, Liu Y D, Bhatt L, Li J R, Thampy V, Kuo C T, Wang B Y, Lee Y, Lee K, Lee J, Goodge B H, Muller D A, Hwang H Y 2025 Nature 638 935
Google Scholar
[16] Zhou G D, Lü W, Wang H, Nie Z H, Chen Y Q, Li Y Y, Huang H L, Chen W Q, Sun Y J, Xue Q K 2025 Nature 640 641
Google Scholar
[17] Bernardini F, Olevano V, Blase X, Cano A 2020 J. Phys. Mater. 3 035003
Google Scholar
[18] Geisler B, Pentcheva R 2020 Phys. Rev. B 102 020502
Google Scholar
[19] Zeng S W, Tang C S, Yin X M, Li C J, Li M S, Huang Z, Hu J X, Liu W, Omar G J, Jani H, Lim Z S, Han K, Wan D y, Yang P, Pennycook S J, Wee A T S, Ariando A 2020 Phys. Rev. Lett. 125 147003
Google Scholar
[20] Lee K, Goodge B H, Li D F, Osada M, Wang B Y, Cui Y, Kourkoutis L F, Hwang H Y 2020 APL Mater. 8 041107
Google Scholar
[21] Tokuda Y, Kobayashi S, Ohnishi T, Mizoguchi T, Shibata N, Ikuhara Y, Yamamoto T 2011 Appl. Phys. Lett. 99 033110
Google Scholar
[22] Bak J, Bae H B, Kim J, Oh J, Chung S Y 2017 Nano Lett. 17 3126
Google Scholar
[23] Goodge B H, Li D F, Lee K, Osada M, Wang B Y, Sawatzky G A, Hwang H Y, Kourkoutis L F 2021 Proc. Natl. Acad. Sci. U. S. A. 118 e2007683118
Google Scholar
[24] Reyren N, Thiel S, Caviglia A D, Kourkoutis L F, Hammerl G, Richter C, Schneider C W, Kopp T, Rüetschi A S, Jaccard D, Gabay M, Muller D A, Triscone J M, Mannhart J 2007 Science 317 1196
Google Scholar
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