High-Temperature Superconducting Multi-Band Radio-Frequency Metamaterial   Atoms
  We report development and measurement of a micro-fabricated compact high-temperature superconducting (HTS) metamaterial atom operating at a frequency as low as $\sim$ 53MHz. The device is a planar spiral resonator patterned out of a {YBa$_2$Cu$_3$O$_{7-\delta}$} (YBCO) thin film with the characteristic dimension of $\sim \lambda_0/1000$, where $\lambda_0$ is the free-space wavelength of the fundamental resonance. While deployment of an HTS material enables higher operating temperatures and greater tunability, it has not compromised the quality of our spiral metamaterial atom and a Q as high as $\sim 1000$ for the fundamental mode, and $\sim 30000$ for higher order modes, are achieved up to 70K. Moreover, we have experimentally studied the effect of the substrate by comparing the performance of similar devices on different substrates. 
Behnood G. Ghamsari, John Abrahams, and Steven M. Anlage
cond-mat.supr-con cond-mat.mes-hall physics.optics