利用W波段高T_c超导-介质谐振器测量YBa_2Cu_3O_(7-x)薄片的毫米波表面阻抗  

MILLIMETER WAVE SURFACE IMPEDANCE OF YBa_2Cu_3O_(7-x) SHEETS MEASURED BY A HIGH-T_c SUPERCONDUCTING-DIELECTRIC RESONATOR AT W-BAND

作　　者：周世平[1] 鲍家善[1] 

机构地区：[1]上海科学技术大学

出　　处：《低温物理学报》1990年第3期174-179,共6页Low Temperature Physical Letters

摘　　要：本文报道利用高 T_c 超导-介质谐振器测量 YBa_2Cu_3O(7-x)表面阻抗随温度的变化.谐振器由蓝宝石管两端加载 YBCO 超导片组成.测量表明,当温度渐降低于80K 时,样品的表面电阻 R_s 迅速下跌;但在低的相对温度下(如t=0.2=T/T_c),样品的 R_s 仍较大,与 BCS 理论预计相去甚远.文中还提出决定λ_L(t)的一种新方法,并从我们的实测数据导出最佳拟合曲线满足λ_L(t)=λ_L(0)(1-t^2)^(-1/2).Temperature dependence of millimeter-wave surface impedance of YBa2Cu3O7-x sheets was measured by using a high-Tc superconducting-dielectric resonator (SDR).The SDR consists of a sapphire tube loaded with two endplates of Y1Ba2Cu3O7-x sheet.It is very suitable for measuring the surface impedance of high-Tc oxide superconductors at w-band.The surface resistance of YBCO samples,R,,drops rapidly below 80K as the temperature decreases,but the excess surface resistance is observed at relatively low temperatures (e.g.,t=0.2=T/Tc).This is not in accord with the predictions of the BCS theory.A new method for determining temperature dependence of penetration depth is proposed.The fitted curve is λ(t)=λ(0) ×(l-t2)-1/2withλ(0) being about 1310A.

关 键 词：阻抗 超导材料 W波段 氧化物 表面 

分 类 号：TM262[一般工业技术—材料科学与工程]