Pr2−xCexCuO4+δ thin films were grown hetero-epitaxially on (001) SrTiO3 substrates using ozone-assisted molecular beam epitaxy. High-quality epilayers with a cerium concentrations of x = 0.15 were grown and characterized electrically, structurally, and by magnetization measurements. The Pr2−xCexCuO4+δ films were found to maintain the tetragonal Nd2CuO4 (T′) crystal structure with a linear dependence of lattice constant on the Ce concentration. The superconductivity of the Pr2−xCexCuO4+δ films was maintained up to x ≈ 0.23 with a Tc up to 12.6 K. For x < 0.15, control of the oxygen concentration δ by annealing is crucial for the induction of superconductivity in Pr2−xCexCuO4+δ and this still holds for x > 0.20. We show that the electron mean free path length $\ell$ may be significantly enhanced by optimizing those annealing conditions. Moreover, the enhancement of $\ell$ leads to a reduction of the upper critical field, suggesting that superconductivity of Pr2−xCexCuO4+δ is to be considered in the clean limit.

We present the results of our systematic investigation of the RE dependency of superconductivity in the parent compounds T’-RE2CuO4 (RE = Pr, Nd, Sm, Eu, Gd, and Tb). Superconducting samples were prepared by metal organic decomposition (MOD). A stringent control of synthesis- and post-annealing-conditions is required to obtain superconducting samples. Superconductivity with a transition temperature (Tconset) ≥ 30 K is achieved for RE = Pr and Nd. By contrast, Tconset is at highest 20 K for RE = Gd. Our results indicate that the induction of superconductivity into T’-RE2CuO4 cuprates strongly depends on the RE3+ ionic size. This trend is discussed from the viewpoint of RE-dependent thermodynamic stability of T’-RE2CuO4. For smaller RE3+ ions, the thermodynamic boundary conditions become tighter.

With the aim of fabricating highly integrated protein microarrays, functional proteins were occluded into a protein crystal, consisting of a proteinaceous occlusion body termed polyhedrin, and the crystals were individually fixed onto a polymer film by using laser trapping and bonding techniques. Individual crystals were trapped by the 1064 nm beam of a Nd3+:YAG laser and placed to the film. The bonding to the film was achieved by irradiating with the single shot of the 800 nm beam of a femtosecond Ti:sapphire laser. Enhanced green fluorescent protein (EGFP) was occluded into the polyhedrin crystal and the crystals were patterned and observed by florescence imaging and single crystal florescence spectroscopy. From these experiments, the biological activity of the bonded crystal was confirmed and their potential as element in protein microarrays was discussed.