Abstract
Recently, high-temperature superconductivity (HTSC) is found in the La(3)Ni(2)O(7)/SrLaAlO(4) ultrathin film with critical temperature T(c) above the McMillan limit at ambient pressure (AP). It is eager to enhance T(c) of La(3)Ni(2)O(7) at AP. We propose that a perpendicular electric field strongly enhances T(c) in the single-bilayer film of La(3)Ni(2)O(7) at AP. Under electric field, the layer with lower potential energy will accept electrons flowing from the other layer to fill in the Ni- 3dx2-y2 orbitals, as the nearly half-filled Ni- 3dz2 orbital cannot accommodate more electrons. 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. 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.