Superconductivity in Sr-doped La₃Ni₂O₇ thin films.

IF 38.5 1区材料科学 Q1 CHEMISTRY, PHYSICAL

Nature Materials Pub Date : 2025-08-18 DOI:10.1038/s41563-025-02327-2

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

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Abstract

Recent studies have demonstrated ambient pressure superconductivity in compressively strained La₃Ni₂O₇ thin films, yet the phase diagram of heterovalent doping-critical for advancing the field-remains underexplored. Here we report superconductivity in Sr²⁺-doped La_3-xSr_xNi₂O₇ films. The superconducting transition temperature (T_c) follows an incomplete dome-like profile, maintaining similar T_c values across a wide doping range (0 ≤ x ≤ 0.21) before diminishing near x ≈ 0.38. Optimally doped films achieve a T_c value of ~42 K, with a high critical current (J_c > 1.4 kA cm^-2 at 2 K) and upper critical fields (μ₀H_c,∥(0) = 83.7 T, μ₀H_c,⟂(0) = 110.3 T). Scanning transmission electron microscopy reveals that oxygen vacancies predominantly occupy planar NiO₂ 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 $d_{z^{2}}$ coupling and contribute to the reduced T_c in strained films.

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sr掺杂La3Ni2O7薄膜的超导性。

最近的研究已经证明了压缩应变La3Ni2O7薄膜的环境压力超导性，但是对于推进该领域至关重要的异价掺杂的相图仍未得到充分的探索。本文报道了Sr2+掺杂La3-xSrxNi2O7薄膜的超导性。超导转变温度（Tc）遵循不完全的圆顶型曲线，在很宽的掺杂范围内（0≤x≤0.21）保持相似的Tc值，然后在x≈0.38附近减小。最佳掺杂膜的Tc值为~42 K，具有较高的临界电流（2 K时Jc >为1.4 kA cm-2）和较高的临界场(μ0Hc,∥（0)= 83.7 T, μ0Hc，⟂(0)= 110.3 T）。扫描透射电镜显示，由于压缩应变，氧空位主要占据平面NiO2位点，而不像大块样品中的顶位空位。此外，拉长的面外Ni-O键比受压体样品中的Ni-O键多4%，可能会削弱层间的dz2耦合，并导致应变膜中Tc的降低。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Nature Materials 工程技术-材料科学：综合

CiteScore

62.20

自引率

0.70%

发文量

221

审稿时长

3.2 months

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