Microwave surface impedance anisotropy of YBa${}_2$Cu${}_3$O${}_x$ single crystals with different oxygen content

Abstract

The linear microwave response of ultra high-quality YBa${}_2$Cu${}_3$O${}_x$ single crystals grown in BaZrO${}_3$ crucibles is measured at 9.4 GHz in rf magnetic fields parallel and perpendicular to the $ab$-plane in the temperature range 5$\le T\le 200$ K. Having found the analytic solution for the magnetic field distribution on the sample surface we determine both the surface impedance $Z_{ab}=R_{ab}+i{X}_{ab}$ in the $ab$-plane and $Z_c=R_c+i{X}_c$ along c-axis of the crystals. For the first time the evolution of the $Z_{ab}(T)$ and $Z_c(T)$ dependences on the same sample and in a wide range of oxygen content is obtained. For $x=6.95$ (optimum oxygen content) the temperature dependence of the imaginary part ${\sigma }_c^{\prime \prime }(T)/{\sigma }_c^{\prime \prime }(0)$ of the c-axis conductivity is found to be strikingly similar to that of ${\sigma }_{ab}^{\prime \prime }(T)/{\sigma }_{ab}^{\prime \prime }(0)$ and becomes more convex with $x$ lowering.

2 pages, 2 figures. To be published in Physica C as LT23 Proceedings

References in corpus (1)

• c-axis electrodynamics of ybco