高温超导混合配对态与磁通涡旋格子

Pairing symmetry and vortex lattice of high temperature superconductors

建立在对基于Gor’kov方法而导出的微观Ginzburg Landau方程的分析揭示了高温超导体YBa2 Cu3O7配对态对称性和磁通涡旋格子结构 .分析指出 ,存在一个格子转变温度T ,当温度高于T 时 ,超导基态显示dx2 -y2 波对称性特征 ;低于该温度s波沟道幅值成为可观的量级 ;超导基态为混合s-dx2 -y2 态 .对应单分量波函数磁通涡旋格子为三角的结构 ;而稳定的斜格子反映出混合波特征 .s与d沟道间耦合约束了磁场下dx2 -x2 波对称性自由度 。

We studied pairing symmetry of YBa 2Cu 3O 7- δ high\|temperature superconductor using a generic Ginzburg\|Landau model.The phase transition between the mixed s\|d x 2-y 2 state and d x 2-y 2 wave was shown.The vortex lattice of a YBa 2Cu 3O 7 superconductor is oblique at the temperature well below the transition temperature T c, where the mixed s\|d x 2-y 2 state is expected to have the lowest energy.Whereas,very close to T c,the d x 2-y 2 wave is slightly lower in energy,and a triangular vortex lattice recovers.The coexistence and the coupling between the s\|and d\|waves would account for the unusual behaviours such as the upward curvature of the upper critical field curve H c2 ( T ).