Reason for high critical current in thin YBCO films prepared by laser ablation from nanostructured target

Abstract

Thin YBCO films prepared by laser ablation from a nanocrystalline target have a high critical current density Jc≈107 A cm-2 at 77 K. To clarify the reason for the high value of Jc, the composition and structure of these films are compared with those deposited from a typical coarse-grained target. According to energy-dispersive x-ray and photoelectron spectroscopic analysis the contents of Y, Ba and Cu are similar in the films of both origins, despite some differences in the compositions of the targets. It is concluded that the high value of Jc in the films prepared from the nanocrystalline target can be explained by pinning of magnetic flux vortices to extended structural defects.

Influence of sequential etching on YBCO films deposited by PLD from a nanostructured target

“…The values of are determined from the magnetic hysteresis loops using the Bean critical state model [5], [6] (1) 10 A cm at 77 K in the as-deposited films and of order of 10 A cm after post-annealing of the film in flowing oxygen are obtained in agreement with earlier results for YBCO films deposited from our nanocrystalline targets [7]. In Fig.…”

“…The concentration of Y is also constant inside the limits of accuracy. The changes in the concentrations are probably partly due to preferential sputtering of Ba and Cu [7] and indicate that the film is uniform throughout its thickness. Also a small Ar peak can be found in the AES spectra after Ar-ion sputtering indicating Ar impurities in the film structure.…”

Influence of Ba2+ consumption and intermediate dwelling during processing of YBa2Cu3O7 nanocomposite films

“…We can therefore conclude that the temperature of the intermediate dwelling step is very crucial to obtain an enhancement of J c for both undoped and ZrO 2 ‐doped YBCO films. This enhancement via introduction of the additional dwelling step may be compared to pulsed laser deposition‐grown samples where the nuclei density can be controlled by deposition temperature, laser frequency, or nano‐crystallinity of the target . It is mentioned in literature that, for CSD‐based materials, the intermediate dwelling step prevents accumulation of particles at the LaAlO 3 interface and hence excessive grain growth and also minimizes agglomeration of nanocrystals in YBCO matrix.…”

Laser deposition from a nanostructured YBaCuO target: Analysis of the plume and growth kinetics of particles on SrTiO3

“…Using a target prepared from YBaCuO nanopowder 19 we have been able to deposit thin superconducting films having the transition temperature T c ϭ90 K and the critical current density J c ϭ8ϫ10 6 A/cm 2 at 77 K in zero magnetic field. 20,21 In comparative measurements on films prepared by PLD from a commercial m target the value of J c ϭ2ϫ10 6 A/cm 2 was achieved.…”