J c Characteristics in high magnetic field and microstructure of RE1+xBa2-xCu3O6+y films

We have investigated the superconducting properties and the microstructure of c-axis oriented Sm1+xBa2-xCu3O6+y (SmBCO) thin films deposited on MgO substrates by pulsed laser deposition (PLD). In particularly, the use of thin c-axis oriented seed layer grown at high temperature enabled us to obtain fully c-axis oriented SmBCO films at relatively low temperature (∼740 deg. C). The values of T c for the present films are within the range of 91.5-92.5 K. From their J c-B characteristics, it has been observed that the superconducting properties of SmBCO (x = 0.04, 0.08) films are superior to those of the YBa2Cu3O7-y thin films for B parallel c, 5 T at 77 K. The J c values of the SmBCO films measuring 2.8 x 105 A/m2 for 5 T of B parallel c at 77 K are comparable to that of NbTi for 5 T at 4.2 K. Furthermore, the superconducting properties in SmBCO change with the substitution of Sm-Ba. The Electron microscopic studies with EDX and S-TEM analysis have revealed that the Sm/Ba ratio fluctuates within the range of x = 0-0.14 with a wavelength of ∼100 nm. High-J c values in high magnetic fields at 77 K demonstrate the potential of REBCO films for high-field applications of oxide superconductor