The effect of Carrier Doping and Thickness on the Electronic Structures of La$3$Ni$2$O$7$ Thin Films

TL;DR

This study uses first-principles calculations to explore how film thickness and carrier doping influence the electronic structure of La3Ni2O7 thin films, providing insights into their superconducting properties at ambient pressure.

Contribution

It offers a theoretical analysis of the effects of doping and thickness on La3Ni2O7's electronic structure, supporting recent experimental findings of superconductivity.

Findings

Optimal doping of 0.4 holes per formula unit metallizes Ni-3d(z^2) states

Formation of γ pockets at the Fermi surface matches ARPES data

Thickness and doping critically modulate electronic properties

Abstract

Recently, the superconductivity of bilayer nickelate La3Ni2O7 has been observed in the thin film at ambient pressure, facilitated by epitaxial strain. Here, we investigate the effects of film thickness and carrier doping on the electronic structure of La3Ni2O7 thin films with thickness of 0.5-3 unit cells (UC) using first-principles calculations. At an optimal doping concentration of 0.4 holes per formula unit for 2UC film, the Ni-"d" _("z" ^"2" ) interlayer bonding state metallizes, leading to the formation of {\gamma} pockets at the Fermi surface, which quantitatively matches the experimental results of angle-resolved photoemission spectroscopy (ARPES). These findings provide theoretical support for recent experimental observations of ambient-pressure superconductivity in La3Ni2O7 thin films and highlight the crucial role of film thickness and carrier doping in modulating electronic properties.