掺锶的镧镍氧化物薄膜中的超导性。

Superconductivity in Sr-doped LaNiO thin films.

作者信息

Hao Bo, Wang Maosen, Sun Wenjie, Yang Yang, Mao Zhangwen, Yan Shengjun, Sun Haoying, Zhang Hongyi, Han Lu, Gu Zhengbin, Zhou Jian, Ji Dianxiang, Nie Yuefeng

机构信息

National Laboratory of Solid State Microstructures, Jiangsu Key Laboratory of Artificial Functional Materials, College of Engineering and Applied Sciences, Nanjing University, Nanjing, China.

Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, China.

出版信息

Nat Mater. 2025 Aug 18. doi: 10.1038/s41563-025-02327-2.

DOI:10.1038/s41563-025-02327-2

PMID:40826178

Abstract

Recent studies have demonstrated ambient pressure superconductivity in compressively strained LaNiO thin films, yet the phase diagram of heterovalent doping-critical for advancing the field-remains underexplored. Here we report superconductivity in Sr-doped LaSrNiO films. The superconducting transition temperature (T) follows an incomplete dome-like profile, maintaining similar T values across a wide doping range (0 ≤ x ≤ 0.21) before diminishing near x ≈ 0.38. Optimally doped films achieve a T value of ~42 K, with a high critical current (J > 1.4 kA cm at 2 K) and upper critical fields (μH(0) = 83.7 T, μH(0) = 110.3 T). Scanning transmission electron microscopy reveals that oxygen vacancies predominantly occupy planar NiO sites-unlike apical-site vacancies in bulk samples-due to compressive strain. Additionally, the elongated out-of-plane Ni-O bonds, exceeding those in pressurized bulk samples by 4%, likely weaken the interlayer coupling and contribute to the reduced T in strained films.

摘要

近期研究已在压缩应变的LaNiO薄膜中证实了常压超导性，但对于推动该领域发展至关重要的异价掺杂相图仍未得到充分探索。在此，我们报道了Sr掺杂的LaSrNiO薄膜中的超导性。超导转变温度（Tc）呈现出不完整的穹顶状分布，在较宽的掺杂范围（0 ≤ x ≤ 0.21）内保持相似的Tc值，在x ≈ 0.38附近开始下降。最佳掺杂的薄膜实现了约42 K的Tc值，具有较高的临界电流（在2 K时J > 1.4 kA cm）和上临界场（μHc2(0) = 83.7 T，μHc2(0) = 110.3 T）。扫描透射电子显微镜显示，由于压缩应变，氧空位主要占据平面NiO位点，这与块状样品中的顶端位点空位不同。此外，面外Ni - O键伸长，比加压块状样品中的键长超出4%，这可能削弱了层间耦合，并导致应变薄膜中Tc降低。