YBa_2Cu_3O_(7-δ)超导厚膜在35GHz频率的毫米波表面电阻

MILLIMETER-WAVE SURFACE RESISTANCE AT YBa_2Cu_3O_(7-δ) SUPERCONDUCTING THICK FILMS AT 35 GHz

用银为隔离层、工作频率为35GHz和模式为TE_(011)的铜谐振腔研究YBa_2Cu_3O_(7_δ)超导厚膜的毫米波表面电阻。应用电泳技术在银衬底上沉积YBa_2Cu_3O_(7_δ)厚膜,经机械加工和精细的表面抛光后作为圆柱型腔的两端面。测量两瑞面为YBa_2Cu_3O_(7_δ)厚膜的腔和铜腔的Q值,计算得到35GHz,77K温度下YBa_2Cu_3O_(7_δ)导厚膜的表面电阻R_5为21.88mΩ,低于同样条件下纯铜的值。YBa_2Cu_3O_(7_δ)从正常态经过T_c进入超导态,穿透深度的变化导致腔的共振频率的增大为11MHz。讨论了YBa_2Cu_3O_(7_δ)的表面处理对R_5的影响。

The millimeter-wave surface resistance of YBa2Cu3O7-δ superconducting thick films was studied using a demountable silver-buffer copper cavity operated at 35 GHz in the TE011 mode. The superconduting films deposited on the silver substrate by the electrophoresis technique were fine machined and polished, and used as the ends of cylinder cavity. The surface resistance Rt of YBa2Cu3O7-δ was obtained from the Q values of the cavity measured before and after substituting the YBa2Cu3O7-δ ends for host ends. The surface resistance Rt of YBa2Cu3O7-δ at 35 GHz, 77K is 21.88mΩ, lower than that of pure copper. The shift in resonant frequency of the cavity related to the change of the penetration depth is 11 MHz at the superconduc-ting transition temperature. The influence of the surface treatment on the surface resistance R5 is discussed.