The discovery of Ni-based superconductors has brought new hope to the field of high-temperature superconductivity. Understanding the dimensional characteristics and anisotropy of nickelate superconductors has become a central focus in current research. However, the nature of the nickelate superconductivity, especially the transition between 2D and 3D superconductivity, remains debated. In this study, we investigated the magnetic field-dependent electrical transport behaviors of infinite-layer nickelates. The La0.8Sr0.2NiO2 films exhibit highly anisotropic superconductivity, which fits well with the 2D Tinkham model, indicating a purely 2D superconducting nature. In contrast, the Nd0.8Sr0.2NiO2 films show isotropic behavior with a mixed 2D + 3D superconducting characteristics. This “mixed 2D + 3D superconducting behavior” is typically associated with the complexity of the electronic band structure in the material. Through a systematic comparison of two model systems with distinct rare-earth orbital contributions, we propose a new perspective based on orbital selectivity. The observed difference likely originates from Nd0.8Sr0.2NiO2 incorporates the Nd <InlineEquation ID="IEq1"> <EquationSource Format="TEX">$5d_{{z}^{2}}$</EquationSource> <EquationSource Format="MATHML"><math display="block"> <mn>5</mn> <msub> <mi>d</mi> <mrow> <msup> <mrow> <mi>z</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msup> </mrow> </msub> </math></EquationSource> </InlineEquation> orbital, adding a 3D component. Its interaction with the Ni <InlineEquation ID="IEq2"> <EquationSource Format="TEX">$3d_{{x}^{2} - {y}^{2}}$</EquationSource> <EquationSource Format="MATHML"><math display="block"> <mn>3</mn> <msub> <mi>d</mi> <mrow> <msup> <mrow> <mi>x</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msup> <mo>−</mo> <msup> <mrow> <mi>y</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msup> </mrow> </msub> </math></EquationSource> </InlineEquation> orbital leads to orbital-selective pairing. Theoretical calculations provide key evidence that the Nd-based system exhibits greater isotropy and 3D character compared to the La-based system. Our study thus suggests that orbital selectivity serves as a critical mechanism governing the superconducting properties, and the distinction between rare-earth elements (such as La and Nd) ultimately influences the dimensional characteristics of superconductivity through this mechanism.

Electrical transport and dimensionality control in infinite-layer nickelates

期刊论文
发表日期：

2026年1月8日

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Yan Zhao,
Minghui Xu,
Lingyi Ao,
Fanrong Lin,
Xiangru Han,
Hangbo Qi,
Ke Zhang,
Huaqian Leng,
Yu Chen,
Wenbo Yang,
Xiaoqiang Wu,
Yong Zhao,
Haiyan Xiao,
Bing Huang,
Yanpeng Liu,
Hongtao Yuan,
Yanrong Li,
Liang Qiao

摘要

The discovery of Ni-based superconductors has brought new hope to the field of high-temperature superconductivity. Understanding the dimensional characteristics and anisotropy of nickelate superconductors has become a central focus in current research. However, the nature of the nickelate superconductivity, especially the transition between 2D and 3D superconductivity, remains debated. In this study, we investigated the magnetic field-dependent electrical transport behaviors of infinite-layer nickelates. The La_0.8Sr_0.2NiO₂ films exhibit highly anisotropic superconductivity, which fits well with the 2D Tinkham model, indicating a purely 2D superconducting nature. In contrast, the Nd_0.8Sr_0.2NiO₂ films show isotropic behavior with a mixed 2D + 3D superconducting characteristics. This “mixed 2D + 3D superconducting behavior” is typically associated with the complexity of the electronic band structure in the material. Through a systematic comparison of two model systems with distinct rare-earth orbital contributions, we propose a new perspective based on orbital selectivity. The observed difference likely originates from Nd_0.8Sr_0.2NiO₂ incorporates the Nd $5d_{{z}^{2}}$ $5 d_{z^{2}}$ orbital, adding a 3D component. Its interaction with the Ni $3d_{{x}^{2} - {y}^{2}}$ $3 d_{x^{2} - y^{2}}$ orbital leads to orbital-selective pairing. Theoretical calculations provide key evidence that the Nd-based system exhibits greater isotropy and 3D character compared to the La-based system. Our study thus suggests that orbital selectivity serves as a critical mechanism governing the superconducting properties, and the distinction between rare-earth elements (such as La and Nd) ultimately influences the dimensional characteristics of superconductivity through this mechanism.