Studies were carried out into the use of pulsed laser ablation deposition (LAD) for the deposition of thin films of superconductors with a high superconductivity temperature (Tc). The preparation, characterization and physical properties of novel high Tc materials were also studied.
Thin films of yttrium barium copper oxide (YBCO) were deposited using plasma assisted laser ablation. The composition of the films was determined by energy dispersive X-ray analysis (EDAX). The state of epitaxial growth was monitored by X-ray diffraction (XRD). The temperature dependence of the resistance of the film was measured by a 4 probe technique and the zero resistance temperature identified.
The correlation between the microstructure of the YBCO films deposited by laser ablation and the growth parameters was demonstrated. The films contain particulates of various sizes. The density of particulates can be reduced by keeping the laser fluence just above the threshold required to initiate the production of plasma at the target surface. Polishing of the target also helps in reducing the particulates. The nature of the particles is not clear. It may be that the particles and the underlying film differ in stoichiometry, undetectable by EDAX.
Several series of bulk ceramic samples and laser ablation thin films of novel high Tc superconductors were prepared. These samples were characterized and physical measurements were made. In particular, high resolution measurements were made of the electrical resistivity and its temperature derivative in zero and applied magnetic field and the thermoelectric power and its temperature derivative.
Funding SchemeCSC - Cost-sharing contracts