Analysis of Transport Properties of MOD YBCO Films With BaZrO3 as Artificial Vortex Pinning Centers

The transport properties of nanocomposite YBa2Cu3O7-x (YBCO) films grown by metal-organic decomposition (MOD) and prepared with a low-fluorine-coating solution on SrTiO3 single-crystal substrates were studied with dc and microwave measurement techniques. As demonstrated in previous studies, the combination of these two techniques is a powerful tool for vortex pinning investigation. The BaZrO3 inclusions (BZO) as artificial pinning centers were introduced into the YBCO matrix by the excess of corresponding Ba and Zr precursor salts to the initial YBCO precursor solution up to 5 mol%. The effect of BZO was clearly observed in magnetic field dependence relations of critical current density (Jc) and the complex surface impedance, i.e., ΔZ, at fixed temperature and magnetic field parallel to the c-axis. The result shows that BZO particles mainly act as isotropic pinning centers. The short-range vortex dynamics was probed by the ∼47.7-GHz microwave surface impedance technique. The derived vortex parameters r and kp were sensitive to the presence of nanoparticles, indicating the effect of BZO on pinning. The joint field dependence relations of Jc and kp help in elucidating the pinning regime in our nanocomposite MOD YBCO/BZO films.