Proximity-induced triplet superconductivity in Rashba materials

Abstract

We study a proximity junction between a conventional s-wave superconductor and a conductor with Rashba spin-orbit coupling, with a specific focus on the spin structure of the induced pairing amplitude. We find that spin-triplet pairing correlations are induced by spin-orbit coupling in both one- and two-dimensional systems due to the lifted spin degeneracy. Additionally, this induced triplet pairing has a component with an odd frequency dependence that is robust to disorder. Our predictions are based on the solutions of the exact Gor'kov equations and are beyond the quasiclassical approximation.Comment: 12 pages, 4 figure

Quasiclassical theory of magnetoelectric effects in superconducting heterostructures in the presence of spin-orbit coupling

“…Our answer fully coincides with the proper expansion to the first order with respect to ∆ so /ε F of the general result for the Gor'kov Green's function, obtained in Ref. 57, what is a good check of the validity of our approach. It is worth to mention here that expressions (37)- (38) are only valid at the distances x < ξ s /(∆ so /ε F ) from the interface (where ξ s is a superconducting coherence length), because physically our approximation can be viewed as a projection of two different quasiparticle trajectories, corresponding to two different spin-orbit split Fermi surfaces, onto the same direction, determined by the Fermi surface in the absence of the spin-orbit splitting.…”

“…A way to such a generalization has already been proposed in the framework of gauge-covariant Green's functions approach 46 . But the results for the proximityinduced triplet correlations in the ballistic limit seem to be not fully coinciding with the results of exact Gor'kov's approach 57 . Also the appropriate normalization condition and boundary conditions for the quasiclassical Green's functions were not considered in Ref.…”

“…More recently, it was reported in several works on the basis of the lattice numerical calculation 56 , a gauge-covariant analytical approach 46 , and, at last, on the basis of exact Gor'kov technique, that triplet superconductivity can be arXiv:1611.01737v2 [cond-mat.supr-con] 23 Sep 2017 generated in Rashba metals by proximity to a singlet superconductor 57 . However, the Gor'kov equations are of very limited use for inhomogeneous problems.…”

Relativistic spin-polarized KKR theory for superconducting heterostructures: Oscillating order parameter in the Au layer of Nb/Au/Fe trilayers

“…It has been known for a long time that spin-orbit coupling (SOC) can influence the symmetry of the order parameter [8] and Josephson currents [9]. However, its impact on noncentrosymmetric systems [10][11][12] and on the proximity effect [13][14][15][16][17] is getting more interest only recently, while it is also a key ingredient in possible realizations for Majorana fermions [18].…”

Scanning tunneling microscopy of superconducting topological surface states inBi2Se3

“…This original result triggered a flood of further theoretical works, some representative examples include Refs. [6][7][8][9][10][11], and a multitude of experimental efforts. The latter span from angleresolved photoemission spectroscopy, scanning tunneling microscopy, point contact, and differential conductance measurements [12][13][14][15][16], through to observations of supercurrents and unusual Josephson Fraunhofer patterns [17][18][19][20][21][22][23][24][25]; experiments on phase coherent transport including multiple Andreev reflections, Fabry-Perot interferometry and Aharonov-Bohm oscillations [26][27][28][29].…”