Possible liquid-nitrogen-temperature superconductivity driven by perpendicular electric field in the single-bilayer film of La<sub>3</sub>Ni<sub>2</sub>O<sub>7</sub> at ambient pressure.

Shao, Zhi-Yan; Ji, Jia-Heng; Wu, Congjun; Yao, Dao-Xin; Yang, Fan · Nat Commun · 2026

basic_science · Level V

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Abstract

Recently, high-temperature superconductivity (HTSC) is found in the La<sub>3</sub>Ni<sub>2</sub>O<sub>7</sub>/SrLaAlO<sub>4</sub> ultrathin film with critical temperature T<sub>c</sub> above the McMillan limit at ambient pressure (AP). It is eager to enhance T<sub>c</sub> of La<sub>3</sub>Ni<sub>2</sub>O<sub>7</sub> at AP. We propose that a perpendicular electric field strongly enhances T<sub>c</sub> in the single-bilayer film of La<sub>3</sub>Ni<sub>2</sub>O<sub>7</sub> at AP. Under electric field, the layer with lower potential energy will accept electrons flowing from the other layer to fill in the Ni- <math xmlns="http://www.w3.org/1998/Math/MathML"><mn>3</mn> <msub><mrow><mi>d</mi></mrow> <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> orbitals, as the nearly half-filled Ni- <math xmlns="http://www.w3.org/1998/Math/MathML"><mn>3</mn> <msub><mrow><mi>d</mi></mrow> <mrow> <msup><mrow><mi>z</mi></mrow> <mrow><mn>2</mn></mrow> </msup> </mrow> </msub> </math> orbital cannot accommodate more electrons. With the enhancement of the filling fraction in the <math xmlns="http://www.w3.org/1998/Math/MathML"><mn>3</mn> <msub><mrow><mi>d</mi></mrow> <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> orbitals in this layer, the interlayer s-wave pairing is suppressed, but the intralayer d-wave pairing in this layer is strongly enhanced. We numerically verify this idea and yield that an imposed voltage of about 0.1 ~ 0.2 volt between layers is enough to realize liquid-nitrogen-temperature HTSC in this single bilayer at AP. Our results appeal for experimental verification.