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  • Open Access

Bosonic Phases across the Superconductor-Insulator Transitions in Infinite-Layer Samarium Nickelate

Menghan Liao1,*,†, Heng Wang2,3,*, Mingwei Yang4,5,*, Chuanwu Cao1,*, Jiayin Tang4, Wenjing Xu4, Xianfeng Wu3, Guangdi Zhou2,3, Haoliang Huang2,3 et al.

Kaiwei Chen1,6,7, Yuying Zhu1,8, Peng Deng1, Jianhao Chen1,8,9,10, Zhuoyu Chen2,3,‡, Danfeng Li4,5,§, Kai Chang1,∥, and Qi-Kun Xue1,2,3,11

  • *These authors contributed equally to this work.
  • †Contact author: liaomh@baqis.ac.cn
  • ‡Contact author: chenzhuoyu@sustech.edu.cn
  • §Contact author: danfeng.li@cityu.edu.hk
  • ∥Contact author: changkai@baqis.ac.cn
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Phys. Rev. X 16, 011029 – Published 19 February, 2026

DOI: https://doi.org/10.1103/rrc1-cqdy

Abstract

Superconductivity arises from the global phase coherence of Cooper pairs. Modulation of phase coherence leads to quantum phase transitions, serving as an important tool for studying unconventional superconductivity. Here, we demonstrate bosonic phases across the superconductor-insulator transition in infinite-layer nickelate superconducting films by the control of spatially periodic network patterns. Magnetoresistance oscillations with a periodicity of h/2e provide direct evidence of 2e Cooper pairing in nickelates. The phase transition is predominantly driven by enhanced superconducting fluctuations, and Cooper pairs are involved in charge transport across the transition. Notably, we observe two types of anomalous metallic phases, emerging, respectively, at finite magnetic fields and down to zero magnetic field. They can be characterized by bosonic excitations, suggesting the dynamic roles of vortices in the ground states. Our work establishes nickelates as a key platform for investigating the rich landscape of bosonic phases controlled via the phase coherence of Cooper pairs.

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Popular Summary

Identifying the microscopic origin of high-temperature superconductivity in nickelates is a significant challenge in condensed matter physics. We addressed this by fabricating spatially periodic networks from nickelate superconducting films and measuring their electronic response. Our experiments revealed magnetoresistance oscillations with a period of h/2e, providing direct evidence of 2e Cooper pairing. We also realized a bosonic superconductor-insulator transition across which Cooper pairs continue to participate in electrical transport. We identified and characterized several quantum phases, including bosonic strange metal and anomalous metallic states. These observations clarify how superconducting fluctuations govern electrical transport and give rise to bosonic phases in nickelates. Our work also opens opportunities for the development of nanofabricated devices based on nickelate superconductors.

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Phys. Rev. X 16, 011029– Published 19 February, 2026
  • Received 6 September 2025
  • Revised 12 December 2025
  • Accepted 26 January 2026
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

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