在雙晶基板上之釔鋇銅氧超導薄膜的晶界弱連接傳輸特性研究

Abstract

我們以脈衝雷射蒸鍍法在鈦酸鍶雙晶基板上，蒸鍍釔鋇銅氧超導薄膜，形 成晶界弱連接超導介面，並研究不同的失配角及不同的氧含量對其傳輸特 性及微橋結構之特性的影響。在臨界電流與溫度的關係中 (Ic∼(1-T/Tc) ^P)，對不同的失配角而言，其指數P值的變化﹐隨角度之增大(24° →36.8°→45°)而減小(2.06→1.95→1.84)﹔對不同氧含量而言﹐在滿 氧(X=7.0)時指數為1.98﹐在缺氧(X=6.9)時指數則變為0.89﹐ P值指示著 超導微橋的結構特性。因此﹐不同失配角的雙晶基板﹐或釔鋇銅氧晶界弱 連接中氧的含量﹐明顯地影響晶界弱連接超導介面的性質。另外﹐我們也 以微波照射此晶界弱連結超導介面﹐發現臨界溫度在微波照射下會被提升 。 The transport properties of the bicrystalline YBCO superconducting thin film grain boundary weak-links deposited on SrTiO3 bicrystal substrates by laser ablation have been investigated systematically. It is found that by varying both the oxygen content and misorientation angle of the grain boundary weak-links, the transport properties characteristics can be reproducibly manipulated. For instance, the functional power (P) of dependence dependent critical current (Ic∼(1-T/Tc) ^P) is found to vary from(2.06→1.95→1.84) with the misorientation angle changing from (24°→36.8°→45°). Whereas when oxygen content varies from fully oxygenated state (X≒7.0 in YBa2Cu3Ox to oxygen-deficient state (X≒6.9) P changes from P≒1.98 to P≒0.89 correspondently. The results demostrated that it is possible to directly manipulate the weak- link properties . In addition, we also found that by irradiating 12.4GHz microwave to the weak-links significant enhancement of superconductivity was realized. The possible physical mechanisms responsible for all the observed results are discussed.