摘要
YBa2Cu3O7（YBCO） thin films have been prepared by thermal coevaporation on LaAlO3（LAO） substrates, and Tl2Ba2CaCu2O8（TBCCO） thin films are synthesized by magnetron sputtering method on LAO substrates. The transition temperature Tc is 90 K forYBCO/LAO and 104 K for TBCCO/LAO. Microwave responses of the films are studied systematically by coplanar resonator technique. Energy gaps of the films obtained are △0 = 1.04kBTc for YBCO films and △0 =0.84kBTc for TBCCO films by analysing the temperature dependence of resonant frequencies of coplanar resonator. Penetration depth at 0 K A0 = 198.nm for YBCO films and A0 = 200 nm for TBCCO films could also be obtained by using the weak coupling theory and two fluid theory. Results of penetration depth and energy gap confirm the weak coupling properties of the films. In addition, microwave surface resistances Rs of YBCO/LAO and TBCCO/LAO are also investigated by analysing the quality factor and insert loss of the coplanar resonator. Surface resistance of TBCCO/LAO is less than that of YBCO/LAO, so that TBCCO/LAO films may have more potential applications.
YBa2Cu3O7（YBCO） thin films have been prepared by thermal coevaporation on LaAlO3（LAO） substrates, and Tl2Ba2CaCu2O8（TBCCO） thin films are synthesized by magnetron sputtering method on LAO substrates. The transition temperature Tc is 90 K forYBCO/LAO and 104 K for TBCCO/LAO. Microwave responses of the films are studied systematically by coplanar resonator technique. Energy gaps of the films obtained are △0 = 1.04kBTc for YBCO films and △0 =0.84kBTc for TBCCO films by analysing the temperature dependence of resonant frequencies of coplanar resonator. Penetration depth at 0 K A0 = 198.nm for YBCO films and A0 = 200 nm for TBCCO films could also be obtained by using the weak coupling theory and two fluid theory. Results of penetration depth and energy gap confirm the weak coupling properties of the films. In addition, microwave surface resistances Rs of YBCO/LAO and TBCCO/LAO are also investigated by analysing the quality factor and insert loss of the coplanar resonator. Surface resistance of TBCCO/LAO is less than that of YBCO/LAO, so that TBCCO/LAO films may have more potential applications.
基金
Project supported by the National Natural Science Foundation of China （Grant No 10474121）.
