Granular Superconductivity in La$_{2}$PrNi$_{2}$O$_{7-δ}$ Thin Films
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arXiv
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| Auteurs principaux: | , , , |
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| Format: | Preprint |
| Publié: |
2026
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| _version_ | 1866911578196017152 |
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| author | Han, Ziao Xiang, Lifen Zhou, X. J. Zhu, Zhihai |
| author_facet | Han, Ziao Xiang, Lifen Zhou, X. J. Zhu, Zhihai |
| contents | Superconductivity realized in bilayer nickelate thin films enables direct spectroscopic and transport studies at ambient pressure. However, a persistent two-step resistive transition remains a major barrier to achieving optimal superconducting properties. Here, we show that the two-step transition in La$_2$PrNi$_2$O$_{7-δ}$ thin films originates from the granular nature of superconductivity, specifically, the coexistence of two distinct superconducting grain phases coupled by a Josephson junction network. A secondary, lower-temperature transition appears in the $R(T)$ curve, even when residual resistance becomes vanishingly small near 30 K. This two-step behavior significantly lowers the zero-resistance transition temperature, $T_{c, zero}$$\approx$ 10 K, and limits advanced spectroscopic studies. Our findings reveal the microscopic mechanism underlying the two-step transition in thin films and underscore the need for improved oxygen homogeneity to achieve bulk superconductivity in this system. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2604_07807 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Granular Superconductivity in La$_{2}$PrNi$_{2}$O$_{7-δ}$ Thin Films Han, Ziao Xiang, Lifen Zhou, X. J. Zhu, Zhihai Superconductivity Superconductivity realized in bilayer nickelate thin films enables direct spectroscopic and transport studies at ambient pressure. However, a persistent two-step resistive transition remains a major barrier to achieving optimal superconducting properties. Here, we show that the two-step transition in La$_2$PrNi$_2$O$_{7-δ}$ thin films originates from the granular nature of superconductivity, specifically, the coexistence of two distinct superconducting grain phases coupled by a Josephson junction network. A secondary, lower-temperature transition appears in the $R(T)$ curve, even when residual resistance becomes vanishingly small near 30 K. This two-step behavior significantly lowers the zero-resistance transition temperature, $T_{c, zero}$$\approx$ 10 K, and limits advanced spectroscopic studies. Our findings reveal the microscopic mechanism underlying the two-step transition in thin films and underscore the need for improved oxygen homogeneity to achieve bulk superconductivity in this system. |
| title | Granular Superconductivity in La$_{2}$PrNi$_{2}$O$_{7-δ}$ Thin Films |
| topic | Superconductivity |
| url | https://arxiv.org/abs/2604.07807 |