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作 者:王晓祺[1] 高波[1] 蔡传兵[1] 刘志勇[1] 鲁玉明[1] 刘金磊[1] 潘成远[1] 应利良[1]
机构地区:[1]上海大学物理系,上海200444
出 处:《低温物理学报》2008年第3期194-198,共5页Low Temperature Physical Letters
基 金:上海市重点学科建设基金(项目编号:T0104);上海市浦江人才计划(项目编号:J14048);上海市重点科技攻关基金(项目编号:055211003);教育部留学回国基金和2006度中德合作科研项目(PPP)资助的课题~~
摘 要:通过三氟乙酸盐-金属有机沉积(TFA-MOD)方法在LaAlO3单晶基片上制备了YBa2Cu3O7-δ(YBCO)高温超导薄膜,并测定在垂直于a^b面的外加交变磁场下薄膜样品的交流磁化率随温度的变化关系.在频率543.2Hz、振幅1 V条件下,样品的超导转变发生在91 K附近.交流磁化率虚部峰值温度TP随着磁场振幅的变大而向低温区移动,随着频率的增大而向高温区移动,这些现象与磁通蠕动模型相一致.峰值温度TP与外交变磁场的振幅HAC满足HCA∝(1-TP/Tc)n的关系,其n^1.55;而与频率之间满足1/TP与lnf的线性关系.可能是由于TAF-MOD薄膜样品中较多孔洞和非位错缺陷的出现使其偏离一般物理气相沉积薄膜样品具有的SNS型连接(n^2).根据频率f与温度T的Arrhenius公式以及二维简约的Bean模型,得到当前薄膜样品的激活能U与电流密度J、以及J与温度T的标度关系.In this study, the YBa2Cu3 O7-δ(YBCO) thin films were prepared on LaAlO3 (100) single crystals by the TFA-MOD method, and the temperature dependence of ac susceptibility of YBCO thin films was measured as a function of frequency and AC field amplitude with the field direction perpendicular to a b plane. The diamagnetic onset temperature of superconducting transition is about 91 K at the frequency of 543.2 Hz and incited coil voltage of 1 V. The peak temperature Tp of ac susceptibility curve' s imaginary part was used as one scaling parameter. The value of Tp becomes lower with enhancing the AC field amplitude, and higher with increasing the frequency, in agreement with the model of flux-creep. It was found that the Tp dependence of field amplitude HA AC can be described as H CA ∝ ( 1 - Tp/Tc) n, and its n - 1.55, the deviation from usual SNS-junction (n - 2 ) HTSC thin films which were prepared by conventional PVD method is believed to originate from the holes of MOD-prepared Samples; and there is an linear dependence of 1/Tp and the frequency Inf. The scaling relationships for activation energy U vs. critical current density J as well as J vs. temperature T were finally deduced from the Arrhenius plot and two-dimensional simplified Bean model.
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