In the realm of high-temperature superconducting materials, the nickel-based double-layer perovskite La₃Ni₂O₇ has emerged as a promising candidate. Under high-pressure conditions, it demonstrates a superconducting transition temperature that surpasses the liquid nitrogen temperature threshold (77K), marking it as the second type of unconventional superconducting material within this temperature range, following the footsteps of copper-based superconductors. Nevertheless, the reliance on high-pressure environments poses significant constraints on its potential for both fundamental research and practical applications.

A collaborative team, led by Professor Yang Fan from the Beijing Institute of Technology (BIT), in conjunction with researchers from Westlake University and Sun Yat-sen University, has proposed an innovative theoretical framework. Their approach involves applying a vertical electric field to single- and double-layer La₃Ni₂O₇ thin films. This strategy aims to induce superconductivity within the liquid nitrogen temperature range at ambient pressure, leveraging interlayer charge transfer as the key mechanism.

The study elucidates that, under the influence of the electric field, electrons migrate from the high-potential layer to the low-potential layer. This migration preferentially fills the Ni-3d_x²-y² orbitals in the low-potential layer, thereby suppressing interlayer s-wave pairing while simultaneously enhancing intralayer d-wave pairing. Theoretical computations suggest that applying an interlayer voltage ranging from 0.1 to 0.2 volts can elevate the electron filling rate of the low-potential layer to a level that closely approximates the optimal doping region for high-temperature superconductivity observed in copper oxides. This, in turn, results in a critical temperature (T_c) that exceeds the liquid nitrogen temperature.

This groundbreaking approach offers a fresh physical mechanism for achieving superconductivity within the liquid nitrogen temperature range at ambient pressure. The pertinent findings have been published in Nature Communications, marking a significant milestone in the field of superconductivity research.