Structural and transport measurements for quasimultilayers of Ir-doped YBa2Cu3O7−δ prepared by pulsed-laser deposition are presented. Due to metallic Ir doping, BaIrO3 particles form during film growth. These nanosized particles, having a perovskite structure, grow epitaxially in cube-on-cube relationship inside the film. A strong increase in pinning force density and, hence, Jc was found.

To study the possibility of enhancing the pinning forces in YBa2Cu3O7−δ films through the introduction of nanosized precipitates, quasi-multilayers of YBa2Cu3O7−δ and a transition metal (TM = Ti,Zr,Hf) were deposited on single-crystal SrTiO3 substrates using pulsed laser deposition. The transition metal layer thickness was chosen to be less than one unit cell, resulting in separated nanoscale islands that form inclusions with perovskite structure BaTM O3 during film growth. These inclusions grow biaxially textured within the film. Whereas the Ti-doped films show a very strong decrease in the critical temperature Tc and, hence, a strong decrease in the critical current density Jc with increasing TM amount for all temperatures, Hf and Zr doping show an increase in Jc for the smallest amounts of doping. An irreversibility field as high as 10.3 T at 77 K was observed in the case of low Hf content.

Compared with mono-rare earth 123 films, ternary rare earth (Nd,Eu,Gd)Ba2Cu3O7−δ (NEG123) films show higher critical current density (Jc) and improved irreversibility field (Hirr), but no increase in the characteristic field corresponding to a crossover from a low-field plateau to a linear region in a log Jc–log H plot. At intermediate fields, Jc vs H scales as H(−0.5±0.05) for NEG123, in contrast to H(−0.73±0.05) for mono-rare earth samples such as Gd123. The slow power decay of Jc vs H together with the improved Jc and Hirr strongly implies that extra flux pinning centers exist in NEG123, which are thought to be noncorrelated stress fields induced by lattice mismatch.

We report on the transport properties of FeSe0.5Te0.5 (FST) thin films fabricated on less-well-textured flexible coated conductor templates with LaMnO3 (LMO) as buffer layers using pulsed laser deposition. The LMO buffer layers exhibit large in-plane misalignment of ∼7.72°, which is unfavorable for cuprate-coated conductors due to the high grain boundaries. The FST thin films show a superconducting transition temperature of 16.8 K, higher than that of bulk materials due to the compressive strain between LMO and FST. Atomic force microscopy observations reveal that island-like features appear at the surfaces of both LMO and FST, confirming the island growth mode. A self-field transport critical-current density of up to 0.43 MA cm−2 at 4.2 K has been observed in FST thin films, which is much higher than that in powder-in-tube processed FST tapes. The films are capable of carrying current densities  of over 105 A cm−2 in the whole applied magnetic field up to 9 T, showing great potential for high-field applications. The results indicate that, for FST, highly textured metal tapes are not needed to produce coated conductors with high performance, which is of great advantage over cuprate-coated conductors.

Instead of NdBa 2 Cu 3 O y (Nd123) bulk crystal, a (001) Nd123/MgO thin film is used as the seed to study single-domain growth in the isothermal solidification of the YBaCuO/Ag system. Various maximum processing temperatures (T max ), down to 1000 • C, are used to fabricate the textured domain. The dependences of nucleation and single-domain growth on undercooling and T max are studied, respectively. For the lower T max processed sample, non-steady growth takes place after a time interval, which is attributed to random nucleation.