Three-Dimensional Electronic Structures in Superconducting Ruddlesden-Popper Bilayer Nickelate Films
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| Main Authors: | , , , , , , , , , , , , , , , |
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| Format: | Preprint |
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2026
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| _version_ | 1866915929397395456 |
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| author | Li, Yueying Xu, Lizhi Lv, Wei Nie, Zihao Wang, Zechao Miao, Yu Shen, Jianchang Zhou, Guangdi Song, Wenhua Wang, Heng Huang, Haoliang He, Junfeng Jia, Jin-Feng Li, Peng Xue, Qi-Kun Chen, Zhuoyu |
| author_facet | Li, Yueying Xu, Lizhi Lv, Wei Nie, Zihao Wang, Zechao Miao, Yu Shen, Jianchang Zhou, Guangdi Song, Wenhua Wang, Heng Huang, Haoliang He, Junfeng Jia, Jin-Feng Li, Peng Xue, Qi-Kun Chen, Zhuoyu |
| contents | Beyond the quasi-two-dimensional (2D) paradigm of cuprates, the role of the third dimension of the Ruddlesden-Popper bilayer nickelates is essential to decoding their superconducting mechanism. Here, using angle-resolved photoemission spectroscopy (ARPES) with varied photon energies, we systematically investigate the electronic band structures in three dimensions for superconducting (La,Pr,Sm)$_3$Ni$_2$O$_7$/SrLaAlO$_4$ thin films (superconducting onset temperature $T_c^{\text{onset}} \sim 48$ K) transferred via a cryogenic ultra-high vacuum suitcase. We reveal an orbital-dependent dimensionality: while the $d{x^2-y^2}$-dominant bands exhibit a quasi-2D character, the $d{z^2}$-dominant band displays a finite $k_z$ dispersion. Finite energy gaps are identified on all observed bands across multiple high-symmetry directions. Systematic temperature-dependent analysis characterizes the superconducting nature of the gap on the $d{z^2}$-derived band, revealing a large gap $Δ\sim 18$ meV and a ratio $2Δ/k_BT_c\sim 8$ exceeding the weak-coupling BCS limit. The suppression of spectral weight near the Fermi level persists above the superconducting transition temperature. Ubiquitous waterfall-like spectral features evidence the presence of electron interactions. These results underscore the role of the $d_{z^2}$ orbital and correlations, placing constraints on theoretical models for nickelate superconductivity. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2604_08430 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Three-Dimensional Electronic Structures in Superconducting Ruddlesden-Popper Bilayer Nickelate Films Li, Yueying Xu, Lizhi Lv, Wei Nie, Zihao Wang, Zechao Miao, Yu Shen, Jianchang Zhou, Guangdi Song, Wenhua Wang, Heng Huang, Haoliang He, Junfeng Jia, Jin-Feng Li, Peng Xue, Qi-Kun Chen, Zhuoyu Superconductivity Strongly Correlated Electrons Beyond the quasi-two-dimensional (2D) paradigm of cuprates, the role of the third dimension of the Ruddlesden-Popper bilayer nickelates is essential to decoding their superconducting mechanism. Here, using angle-resolved photoemission spectroscopy (ARPES) with varied photon energies, we systematically investigate the electronic band structures in three dimensions for superconducting (La,Pr,Sm)$_3$Ni$_2$O$_7$/SrLaAlO$_4$ thin films (superconducting onset temperature $T_c^{\text{onset}} \sim 48$ K) transferred via a cryogenic ultra-high vacuum suitcase. We reveal an orbital-dependent dimensionality: while the $d{x^2-y^2}$-dominant bands exhibit a quasi-2D character, the $d{z^2}$-dominant band displays a finite $k_z$ dispersion. Finite energy gaps are identified on all observed bands across multiple high-symmetry directions. Systematic temperature-dependent analysis characterizes the superconducting nature of the gap on the $d{z^2}$-derived band, revealing a large gap $Δ\sim 18$ meV and a ratio $2Δ/k_BT_c\sim 8$ exceeding the weak-coupling BCS limit. The suppression of spectral weight near the Fermi level persists above the superconducting transition temperature. Ubiquitous waterfall-like spectral features evidence the presence of electron interactions. These results underscore the role of the $d_{z^2}$ orbital and correlations, placing constraints on theoretical models for nickelate superconductivity. |
| title | Three-Dimensional Electronic Structures in Superconducting Ruddlesden-Popper Bilayer Nickelate Films |
| topic | Superconductivity Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2604.08430 |