Improved superconducting properties of SmBa₂Cu₃O_7−δ films using YBa₂Cu₃O_7−δ buffer layers

Abstract

Abstract We report the fabrication of SmBa2Cu3O7−δ (Sm123) films on YBa2Cu307−δ(Y123) buffer layers 10–20nm thick using pulsed-laser deposition. Significant improvement in the superconducting properties of Sm 123 such as Tc and Jc has been observed when Y123 buffer layers are used on various substrates (LaAlO3, SrTiO3, NdGaO3 and CeO2/(yttrium-stabilized zirconia)). The buffered Sm 123 films have a high Tc of 93.1 K and a high Jc of 1.9 × 106 Acm−2 at 75 K in zero magnetic field. Compared with Y123, the buffered Sm123 samples have com-parable microwave surface resistance values and pinning characteristics with reduced anisotropy measured by the angle-dependent Ic. The effects of the Y123 buffer layer on the superconducting properties of Sm 123 are investigated and discussed in relation to the initial film growth chemistry and the substitution of Sm on Ba sites.