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

Summary

Given the urgent need to enhance the superconducting transition temperature (T_c) of La₃Ni₂O₇ single- and double-layer thin films under ambient pressure, this study proposes applying a vertical electric field to drive charge transfer for superconductivity enhancement. The vertical field drives electrons from higher-potential layers to lower-potential layers; since the Ni 3dz² orbital is nearly half-filled and cannot accommodate additional electrons, the inflowing electrons primarily fill the 3dx²-y² orbitals of the lower-potential layer, thereby increasing its filling rate. Using a simplified single-orbital model and a comprehensive two-orbital model, combined with slave-boson mean-field theory and density matrix renormalization group methods, numerical calculations reveal that the increased filling suppresses interlayer s-wave pairing but strongly enhances intralayer d-wave pairing, causing the bottom-layer-dominated d-wave superconductivity to rise rapidly. When the interlayer voltage reaches approximately 0.1–0.2 V, T_c can surpass the liquid nitrogen temperature (around 77 K), achieving high-temperature superconductivity in the liquid nitrogen temperature range under ambient pressure. This approach requires no high pressure and avoids chemical doping disorder, providing a feasible route to realize high-T_c superconductivity in La₃Ni₂O₇ ultrathin films, which warrants further experimental verification.

Materials

• La₃Ni₂O₇

Methods

• SBMF
• DMRG
• tight-binding modeling

Keywords

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

Highlights

• 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.

Conclusions

• 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.

Main claims

• Perpendicular electric field can induce liquid-nitrogen-temperature superconductivity in single-bilayer La₃Ni₂O₇ film at ambient pressure
  • Evidence: 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
  • Evidence: 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'

Workflow

• model_construction — Perpendicular electric field drives charge transfer from top to bottom layer
  • Materials: La₃Ni₂O₇ single-bilayer film
  • Methods: one-orbital and two-orbital Hubbard models
  • Observations: electron filling; pairing symmetry
• slave_boson_mean_field_analysis — Intrabottom-layer d-wave pairing enhanced with voltage; T_c can exceed 77K
  • Materials: Derived models
  • Methods: slave-boson mean-field theory
  • Observations: 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
  • Materials: One-orbital bilayer model
  • Methods: DMRG
  • Observations: pairing correlation functions