earticle

영어

We investigated the flux pinning properties of both 10 mol% Zr-and Sn-doped YBa2Cu3O7-δ (YBCO) films with the same thickness of ~350 nm for a comparative purpose. The films were prepared on the SrTiO3 (STO) single crystal substrate by the metal-organic deposition (MOD) process. Compared with Sn-doped YBCO film, Zr-doped one exhibited a significant enhancement in the critical current density (Jc) and pinning force density (Fp). The anisotropic Jc,min/Jc,max ratio in the field-angle dependence of Jc at 77 K for 1 T was also improved from 0.23 for Sn-doped YBCO to 0.39 for Zr-doped YBCO. Thus, the highest magnetic Jc values of 9.0 and 2.9 MA/cm2 with the maximum Fp (Fp,max) values of 19 and 5 GN/m3 at 65 and 77 K for H // c, respectively, could be achieved from Zr-doped YBCO film. The stronger pinning effect in Zr-doped YBCO film is attributable to smaller BaZrO3 (BZO) nanoparticles (the average size ≈ 28.4 nm) than YBa2SnO5.5 (YBSO) nanoparticles (the average size ≈ 45.0 nm) incorporated in Sn-doped YBCO film since smaller nanoparticles can generate more defects acting as effective flux pinning sites due to larger incoherent interfacial area for the same doping concentration.