CNR-SPIN, I-84084 Fisciano (Salerno), Italy and Dipartimento di Fisica E. R. Caianiello, Università di Salerno, I-84084 Fisciano (Salerno), Italy.
Phys Rev Lett. 2013 Jun 28;110(26):267002. doi: 10.1103/PhysRevLett.110.267002. Epub 2013 Jun 26.
We show that a spontaneous magnetic moment may appear at the edge of a spin-triplet superconductor if the system allows for pairing in a subdominant channel. To unveil the microscopic mechanism behind such an effect, we combine numerical solution of the Bogoliubov-de Gennes equations for a tight-binding model with nearest-neighbor attraction, and the symmetry based Ginzburg-Landau approach. We find that a potential barrier modulating the electronic density near the edge of the system leads to a nonunitary superconducting state close to the boundary where spin-singlet pairing coexists with the dominant triplet superconducting order. We demonstrate that the spin polarization at the edge appears due to the inhomogeneity of the nonunitary state and originates in the lifting of the spin degeneracy of the Andreev bound states.
我们表明,如果系统允许在次要通道中配对,则自旋三重态超导体的边缘可能会出现自发磁矩。为了揭示这种效应背后的微观机制,我们将紧束缚模型的 Bogoliubov-de Gennes 方程的数值解与基于对称的吉布斯-朗道方法相结合。我们发现,调节系统边缘附近电子密度的势垒导致接近边界的非幺正超导状态,其中自旋单配对与主要的三重超导序共存。我们证明,由于非幺正态的不均匀性,边缘处的自旋极化出现,并且源于安德烈夫束缚态的自旋简并的消除。