レーザ蒸着法で作製したＲＥ１＋ｘＢａ２‐ｘＣｕ３Ｏ６＋ｙ膜の高磁場中高Ｊｃ特性

Abstract

We have investigated the superconducting properties and the microstructure of the c -axis oriented Sm1+xBa2−xCu3O6+y(Sm-123) and GdBa2Cu3O6+y(Gd-123) thin films deposited on MgO substrates deposited by pulsed laser deposition (PLD). From their Jc-B characteristics, it has been observed that the superconducting properties of Sm-123 (x =0), Sm-123 (x =0.08) and Gd-123 are superior to those of the YBa2Cu3O7−y thin films for B//c, 5 T at 77 K. The Jc values of the Sm-123 (x =0) films measuring 7×108 A/m2 for 5 T at 77 K are comparable to that of NbTi for 5 T at 4.2 K. Furthermore, the superconducting properties in Sm-123 change with the substitution of Sm-Ba. By observing the c -axis oriented high-Jc Sm-123 thin films using the cross-section transmission electron microscopy, we detected the existence of finely dispersed a -axis oriented domains with a size of about 10 nm in the c -axis oriented matrix. Electron microscopic studies with EDX have revealed that the Sm/Ba ratio fluctuates within the range of x =0 to 0.14 with a wavelength of ∼400 nm. It is considered that these domains are formed by a cation combining with the substituted Sm/Ba and a growth temperature difference on the a -axis oriented Sm-123 phase which has a c -axis orientation phase. High-Jc values in high magnetic fields at 77 K demonstrate the potential of REBCO films for high-field applications of oxide superconductor.