Inhomogeneities in YBa2Cu3O7 thin films with reduced thickness

Abstract

Morphology and physical properties of mono-(YBa 2 Cu 3 O 7) and multilayered (YBa 2 Cu 3 O 7 /SmBa 2 Cu 3 O 7 / YBa 2 Cu 3 O 7) superconducting thin films with thickness ranging from 90 nm to 28 nm have been investigated. For both types of samples, the superconducting properties degraded with reduction of film thickness. Structural and electromagnetic properties were visualized through scanning electron microscopy and magneto-optical imaging, respectively, and revealed high level of inhomogeneity for thinner (<58>nm) samples. However, samples with thickness above 58 nm showed enhanced homogeneity, which explains better superconducting characteristics observed in these films. Results of this work demonstrate that multilayering approach performed by conventional laser ablation results in degradation of superconducting properties in films with thickness below 90 nm, although has positive impact on morphology of these films, which is crucial for device fabrication process.

Growth of superconducting and ferroelectric heterostructures

“…It is notable a small decrease in the critical temperature compared with the first group and that can be explained by the decrease of the thickness of the samples (from 143 to 57 nm) since it is already reported similar results. 105 The YBCO_3Hz and YBCO_1Hz presented different types of contributions for the superconducting transition. In the case of the former, the two contributions (two peaks in the first derivative) have different critical temperatures as shown in the inset of the figure and this can be explained with a non-homogeneous distribution of oxygen inside the sample, creating zones with different critical temperature.…”