Improvement of microwave characteristics for high-T _c superconductor (YBCO) films by ion irradiation treatment

Abstract

Measurements of the microwave surface impedance for high-temperature superconductor (HTS) YBa2Cu3O7-x(YBCO) films irradiated by 3 MeV Au2+ ions at three irradiation doses (1010cm-2, 1011cm-2, and 1012cm-2) were carried out at different temperatures (below the critical temperature Тс∼90К) and various rf current amplitudes by use of microstrip resonator technique. Noticeable decrease of the surface resistance and enhancement of the linear response range at low temperatures were observed for moderately irradiated film exposed to irradiation dose 1011cm-2, while at higher irradiation doses (1012cm-2) increase of the surface resistance and decrease of the linear response range were observed for all temperatures below Tc. These results are discussed in the framework of phenomenological theory for microwave response of superconductors with nano-sized structural defects.

Control of the effective value of the critical current of the RF SQUID by the high-frequency electromagnetic field

“…However, the experiments made in this work demonstrate that variations of the HF field amplitude effectively transform the characteristics of RF SQUIDs from a classical hysteretic regime to a regime formally similar to nonhysteretic. 8,9 Such control of the main parameter of the RF SQUID is particularly interesting for two-zone superconductors [10][11][12] and HTSs. 13,14 Somewhat unexpectedly, the regions with conversion coefficients exceeding the classical value for the hysteretic regime were observed at the AFCs of RF SQUIDs during this transformation.…”

Review on Microwave Surface Resistance of High Temperature Superconductor Yttrium Barium Copper Oxide

“…Transmission line techniques are proven methods used to assess the microwave surface resistance (Rs) of Yttrium Barium Copper Oxide (YBCO) superconductors, as shown in multiple investigations [45]. These methods entail incorporating YBCO samples into various transmission line configurations, such as microstrip lines or coplanar waveguides.…”