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Persistent paramagnons in high-temperature infinite-layer nickelate superconductors.
Yujie Yan1,2, Ying Chan1,2, Xunyang Hong1,2,3
1Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong, China.
Nature Communications
|May 20, 2026
Summary
High-temperature superconductivity in SmNiO2 shows enhanced performance. Spin fluctuations are key, but magnetic interactions differ from cuprates, revealing unique superconducting mechanisms in nickelates.
Area of Science:
- Condensed Matter Physics
- Materials Science
Background:
- Hole-doped SmNiO2 exhibits record-high superconducting transition temperatures (Tc) among infinite-layer nickelates.
- Understanding the electronic structure and magnetic interactions is vital for elucidating the mechanism of enhanced superconductivity.
Purpose of the Study:
- Investigate the electronic structure and magnetic interactions in Sm-based infinite-layer nickelates (SECNO).
- Explore the relationship between magnetic interactions and superconductivity in these novel materials.
Main Methods:
- Utilized Ni L-edge resonant inelastic x-ray scattering (RIXS) on superconducting Sm1-x-yEuxCalyNiO2 (SECNO) thin films.
- Analyzed dispersive paramagnonic excitations in optimally and overdoped samples.
Main Results:
- Observed dispersive paramagnonic excitations, supporting a spin-fluctuation-mediated pairing scenario.
- Found a ~20% reduction in effective exchange coupling strength in Sm-based nickelates compared to Pr-based ones, despite a two-fold enhancement in Tc.
- Highlighted contrasting behavior with hole-doped cuprates, where magnetic interactions positively correlate with Tc.
Conclusions:
- Spin fluctuations play a crucial role in the enhanced superconductivity of Sm-based nickelates.
- The reduced magnetic interaction strength in Sm-based nickelates, despite higher Tc, suggests distinct superconducting mechanisms compared to cuprates.
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