Thickness-induced insufficient oxygen reduction in La(2-x)CexCuO4 thin films

TL;DR

This study investigates how film thickness affects oxygen reduction and superconducting properties in La(2-x)CexCuO4 thin films, revealing that thinner films exhibit less oxygen reduction due to substrate-induced stress.

Contribution

It demonstrates the impact of film thickness and substrate stress on oxygen reduction and superconductivity in electron-doped cuprate thin films, highlighting the importance of thickness control.

Findings

Residual resistivity increases with film thickness.

Hall coefficient shifts negatively as thickness increases.

c-axis lattice constant increases with decreasing thickness.

Abstract

A series of electron-doped cuprate La(2-x)CexCuO4 thin films with different thicknesses have been fabricated and their annealing time are adjusted carefully to ensure the highest superconducting transition temperature. The transport measurements indicate that, with the increase of the film thickness (<100 nm), the residual resistivity increases and the Hall coefficient shifts in the negative direction. Further more, the X-ray diffraction data reveal that the c-axis lattice constant c0 increases with the decrease of film thickness. These abnormal phenomena can be attributed to the insufficient oxygen reduction in the thin films. Considering the lattice mismatching in the ab-plane between the SrTiO3 substrates and the films, the compressive stress from the substrates may be responsible for the more difficult reduction of the oxygen in the thin films.