Possible Liquid-Nitrogen-Temperature Superconductivity Driven by Perpendicular Electric Field in the Single-Bilayer Film of La₃Ni₂O₇ at Ambient Pressure

摘要

针对La₃Ni₂O₇单双层薄膜在常压下的超导转变温度（T_c）亟待提升的需求，本研究提出通过施加垂直电场驱动电荷转移来增强其超导电性。垂直电场使电子从高电势层流向低电势层，由于Ni的3dz²轨道已接近半满无法容纳更多电子，流入电子主要填充低电势层的3dx²-y²轨道，从而增加该层的填充率。利用简化的单轨道模型和全面的双轨道模型，结合奴隶玻色子平均场理论与密度矩阵重正化群方法，数值计算发现：填充率的增加会抑制层间s波配对，但强烈增强层内d波配对，使得底层主导的d波超导迅速上升。当层间电压达到约0.1~0.2伏时，T_c可超越液氮温度（约77 K），在常压下实现液氮温区的高温超导。该方案无需高压且避免化学掺杂无序，为在La₃Ni₂O₇超薄膜中实现高T_c超导提供了可行途径，需要实验进一步验证。

材料

• La₃Ni₂O₇

方法

• SBMF
• DMRG
• tight-binding modeling

关键词

• electric field induced superconductivity
• d wave pairing
• charge transfer
• ambient pressure superconductivity

亮点

• Proposes a viable route to achieve liquid-nitrogen-temperature superconductivity in La₃Ni₂O₇ without high pressure or chemical doping.
• Predicts that the d-wave superconducting state coexists with an interlayer s-wave pseudogap, breaking time-reversal symmetry.
• The idea leverages charge transfer via electric field, similar to oxide heterostructures, to mimic optimal doping in cuprates.

结论

• A perpendicular electric field drives electrons to fill the bottom-layer Ni-3dx2-y2 orbitals, enhancing intralayer d-wave pairing.
• Interlayer s-wave pairing is suppressed by field-induced charge imbalance, while intralayer d-wave pairing is strongly enhanced.
• Applying 0.1-0.2 V between layers can yield T_c above liquid nitrogen temperature (77 K) in a single-bilayer La₃Ni₂O₇ film at ambient pressure.

主要论断

• Perpendicular electric field can induce liquid-nitrogen-temperature superconductivity in single-bilayer La₃Ni₂O₇ film at ambient pressure
  • 证据: From abstract: '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'
• Electric field drives electrons to fill dx2-y2 orbitals in bottom layer, suppressing interlayer s-wave and enhancing intralayer d-wave pairing
  • 证据: From abstract: 'With the enhancement of the filling fraction in the 3dx2-y2 orbitals in this layer, the interlayer s-wave pairing is suppressed, but the intralayer d-wave pairing in this layer is strongly enhanced'

研究流程

• model_construction — Perpendicular electric field drives charge transfer from top to bottom layer
  • 材料: La₃Ni₂O₇ single-bilayer film
  • 方法: one-orbital and two-orbital Hubbard models
  • 观察: electron filling; pairing symmetry
• slave_boson_mean_field_analysis — Intrabottom-layer d-wave pairing enhanced with voltage; T_c can exceed 77K
  • 材料: Derived models
  • 方法: slave-boson mean-field theory
  • 观察: pairing gap amplitude; critical temperature
• density_matrix_renormalization_group_simulations — DMRG confirms transition from interlayer s-wave to intralayer d-wave pairing under electric field
  • 材料: One-orbital bilayer model
  • 方法: DMRG
  • 观察: pairing correlation functions