Study on spin-triplet high-temperature superconducting cooper pairs

为了实现特殊的自旋三重态高温超导态，我们研究了自旋单线态氧化物或氮化物超导体和磁性材料异质结的制备和电学性质。在a轴取向薄膜中可以成功制备出无限层氧化超导Sr0.9La0.1CuO2，该薄膜具有较长的超导相干长度，有利于结界面的控制。在a轴超导Sr0.9La0.1CuO2薄膜和铁磁性Sr2CrReO6或反铁磁性SrLaVMoO6薄膜之间实现了异质外延生长。研究了超薄磁层对NbN超导结的影响。具有1 nm厚铁磁CoFe插入层的结表现出不对称的弗劳恩霍夫模式，且在零场处存在最小的约瑟夫森超电流，这表明由于结界面的磁不均匀性，可能存在自旋三重态铜对。

To realize peculiar spin-triplet high-temperature superconducting states, we have investigated preparation and electrical properties of hetero-junctions with spin-singlet oxide, or nitride superconductors and magnetic materials.Infinite-layer oxide superconducting Sr0.9La0.1CuO2 can be successfully obtained in a-axis oriented thin films, which are favorable for the control of the junction interfaces owing to their long superconducting coherence length. Hetero epitaxial growth between a-axis superconducting Sr0.9La0.1CuO2 films and ferromagnetic Sr2CrReO6 or antiferromagnetic SrLaVMoO6 films was also achieved.The effect of insertion of ultra-thin magnetic layers in NbN superconducting junctions was examined. The junctions with a 1 nm-thick ferromagnetic CoFe insertion layer exhibited asymmetric Fraunhofer patterns with a minimum of Josephson supercurrent at zero field, which suggests the possibility of existence of spin-triplet cooper pairs due to magnetic inhomogeneity of junction interfaces.