Epitaxial growth of Gd₂₋ₓCeₓCuO₄ thin films

We have grown (001)-oriented thin films of Gd₂₋ₓCeₓCuO₄ with cerium composition 0 < x < 0.2 by state-of-the-art reactive molecular beam epitaxy and characterized them by x-ray diffraction and transport measurements. A systematical change in the c-axis length upon cerium doping indicates that single-phase films were obtained for the whole doping range. Based on a log po₂ - 1/T phase diagram in combination with reflection high energy electron diffraction (RHEED), phase stability has been determined in order to achieve optimized reduction conditions. Gd₂₋ₓCeₓCuO₄ thin films even after controlled reductions treatment did not show superconductivity in the whole range of Ce concentration studied. However, the room temperature resistivity of optimally reduced Gd₂₋ₓCeₓCuO₄ thin films shows a minimum at around xCe = 0.16. Our results on the growth and characterization of Gd₂₋ₓCeₓCuO₄ thin films on (100) SrTiO3 substrates are described in detail.