Epitaxial growth of Fe-based superconductor thin films

The Fe-based superconductors (FBS), discovered in 2008, are not only interesting for possible applications due to their large upper critical fields and low anisotropies, but also for basic understanding of unconventional superconductivity. With their properties, they constitute a link between the classic low-T_c superconductors (low anisotropies, low thermal fluctuations, s-wave type symmetry) and the oxocuprates (T_c up to 55 K, large H_c2, unconventional pairing). Their multi-band nature reminds of MgB₂. We prepare thin films of FBS in the so called 122 family, namely Co- and P-doped BaFe₂As₂ to investigate application relevant properties, such as critical current density J_c, by pulsed laser deposition using a frequency-tripled Nd:YAG laser (λ = 355 nm). Microstructure and chemical composition will be investigated by XRD, AFM and SEM, and electrical transport using a 14 T PPMS. The results are compared to literature data on films grown at different wavelengths.