Comparative study of carrier concentration and reciprocal space mapping in SmBa₂Cu₃O_y thin films with high critical current density

We have reported SmBa₂Cu₃O_y (Sm123) films prepared using a pulsed laser deposition (PLD) method. In particularly, Sm123 thin films prepared using a low temperature growth technique (LTG) could achieve a high-J_c in a magnetic field at 77 K comparable to that in a Nb-Ti wire at 4.2 K. In order to clarify a mechanism of high-J_c in LTG-Sm123 films, we compared an X-ray reciprocal space mapping (RSM) and a carrier concentration in the LTG films with those in PLD films. Although a Sm123 peak split on the RSM which corresponds to an orthorhombic structure, was observed in the PLD films with a thickness of ≥100 nm, the LTG films did not show such split. Further, from an annealing time dependence of the carrier concentration, a carrier injection into the LTG films tended to be difficult as compared to that into the PLD films. These facts imply that the LTG technique gives a high crystallinity. Therefore, we concluded that one of reasons of the high-J_c in the LTG films was an improvement of crystalline uniformity such as an orientation and a lattice constant.