The recent discovery of superconductivity with a transition temperature Tc exceeding 40 K in La3Ni2O7 and (La, Pr)3Ni2O7 thin films at ambient pressure marks a significant breakthrough in the field of nickelate superconductors. Using density functional theory (DFT), we propose a double-stacked two-orbital effective model for La3Ni2O7 thin film based on the Ni − eg orbitals. Our analysis of the Fermi surface reveals three electron pockets (<InlineEquation ID="IEq1"> <EquationSource Format="TEX">$\alpha ,{\alpha }^{{\prime} },\beta$</EquationSource> <EquationSource Format="MATHML"><math> <mi>α</mi> <mo>,</mo> <msup> <mrow> <mi>α</mi> </mrow> <mrow> <mo>′</mo> </mrow> </msup> <mo>,</mo> <mi>β</mi> </math></EquationSource> </InlineEquation>) and two hole pockets (<InlineEquation ID="IEq2"> <EquationSource Format="TEX">$\gamma ,{\gamma }^{{\prime} }$</EquationSource> <EquationSource Format="MATHML"><math> <mi>γ</mi> <mo>,</mo> <msup> <mrow> <mi>γ</mi> </mrow> <mrow> <mo>′</mo> </mrow> </msup> </math></EquationSource> </InlineEquation>), where the additional <InlineEquation ID="IEq3"> <EquationSource Format="TEX">${\alpha }^{{\prime} }$</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mrow> <mi>α</mi> </mrow> <mrow> <mo>′</mo> </mrow> </msup> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq4"> <EquationSource Format="TEX">${\gamma }^{{\prime} }$</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mrow> <mi>γ</mi> </mrow> <mrow> <mo>′</mo> </mrow> </msup> </math></EquationSource> </InlineEquation> pockets arise from inter-stack interactions. Furthermore, we introduce a high-energy model that incorporates O−p orbitals to facilitate future studies. Calculations of spin susceptibility within the random phase approximation (RPA) indicate that magnetic correlations are enhanced by nesting of the γ pocket, which is predominantly derived from the Ni<InlineEquation ID="IEq5"> <EquationSource Format="TEX">$-{d}_{{z}^{2}}$</EquationSource> <EquationSource Format="MATHML"><math> <mo>−</mo> <msub> <mrow> <mi>d</mi> </mrow> <mrow> <msup> <mrow> <mi>z</mi> </mrow> <mrow> <mn>2</mn> </mrow> </msup> </mrow> </msub> </math></EquationSource> </InlineEquation> orbital. Our results provide a theoretical foundation for understanding the electronic and magnetic properties of La3Ni2O7 thin films.

Electronic structures and multi-orbital models of La₃Ni₂O₇ thin films at ambient pressure

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2025年11月21日

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Xunwu Hu,
Wenyuan Qiu,
Cui-Qun Chen,
Zhihui Luo,
Dao-Xin Yao

摘要

The recent discovery of superconductivity with a transition temperature T_c exceeding 40 K in La₃Ni₂O₇ and (La, Pr)₃Ni₂O₇ thin films at ambient pressure marks a significant breakthrough in the field of nickelate superconductors. Using density functional theory (DFT), we propose a double-stacked two-orbital effective model for La₃Ni₂O₇ thin film based on the Ni − e_g orbitals. Our analysis of the Fermi surface reveals three electron pockets ( $\alpha ,{\alpha }^{{\prime} },\beta$ $α, α^{'}, β$ ) and two hole pockets ( $\gamma ,{\gamma }^{{\prime} }$ $γ, γ^{'}$ ), where the additional ${\alpha }^{{\prime} }$ $α^{'}$ and ${\gamma }^{{\prime} }$ $γ^{'}$ pockets arise from inter-stack interactions. Furthermore, we introduce a high-energy model that incorporates O−p orbitals to facilitate future studies. Calculations of spin susceptibility within the random phase approximation (RPA) indicate that magnetic correlations are enhanced by nesting of the γ pocket, which is predominantly derived from the Ni $-{d}_{{z}^{2}}$ $- d_{z^{2}}$ orbital. Our results provide a theoretical foundation for understanding the electronic and magnetic properties of La₃Ni₂O₇ thin films.

Electronic structures and multi-orbital models of La3Ni2O7 thin films at ambient pressure

摘要

Electronic structures and multi-orbital models of La₃Ni₂O₇ thin films at ambient pressure