Influence of in-plane 0-45 degree grain boundary on microwave surface resistance of c-axis YBa sub(2)Cu sub(3)O sub(y) films on MgO substrate

摘要

The effect of in-plane 0-45 degree grain boundaries on surface resistance (R sub(s)) of c-axis YBa sub(2)Cu sub(3)O sub(y) (YBCO) films on MgO substrates is discussed. Samples that have various densities of 45 degree rotated grains were prepared using a self-template technique. The R sub(s) values at 22 GHz were measured by the dielectric resonator method using a cryocooler. The R sub(s) systematically changed corresponding to the amount of 0-45 degree grain boundaries. Conspicuous feature of the films including 0-45 degree grain boundaries is a large residual surface resistance. The R sub(s) of almost perfectly in-plane aligned YBCO film scaled to 10 GHz were 0.12 m Omega at 20 K and 0.67 m Omega at 77 K on the assumption of tan delta identical with 0, respectively.