High quality YBa2Cu307/PrBa2Cu307 superlattices with desired thicknesses of each component were fabricated by laser deposition. Superconductivity was studied by varying both YBa2Cu3O7 and PrBa2Cu307 layer thicknesses. The results indicated that an isolated single unit cell YBa2Cu3O7 layer (nominal thickness of 12 AËš) is superconducting. The increase of Tcfrom the lower value of a single unit cell layer to 90 K in thick films and the enhancement of Tcfor a given thickness of YBa2Cu3O7 when the PrBa2Cu307 layers decreased to less than ~30 AËšcould be attributed to the interlayer coupling effect. Superconducting transitions of superlattices in applied magnetic fields were studied. The interlayer coupling effect on vortices can be seen by comparing the transition curves in high magnetic fields of thick film, ultrathin film and superlattice. For the samples with very thin YBa2Cu3O7 layers, similar results to vortex-antivortex pair phase transition was observed by measuring the temperature dependence of resistance, magnetoresistance, and I-V curves, indicating a strong two dimensional behavior in very thin YBa2Cu3O7 films.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Electrical and Electronic Engineering