Role of interface and valley-mixing scattering in a ferromagnetic silicene/superconductor junction

Abstract

We theoretically investigate the subgap transport in a ferromagnetic silicene/superconductor junction and highlight the role of the interface. It is demonstrated that the subgap conductance spectra for the continuous and discontinuous interface models are significantly different. In particular, the intravalley Andreev reflection (AR) may occur at the discontinuous interface, and then the subgap conductance will be remarkably enhanced when the silicene sheet is highly valley polarized. This novel AR resulted from the valley-mixing scattering, which is absent in the continuous interface model. The influence of the interface coupling strength on the subgap conductance is also computed. Our results can be directly tested experimentally using scanning tunnel microscope measurements and/or point-contact spectroscopy.

Photoinduced spin-polarized transport and controllable valley-triplet pairing states in a silicene-superconductor junction

“…. In light of our theory, the photoinduced spin polarization is entirely different with that induced by the exchange energy in the ferromagnetic silicene [35,36]. The former is a result of different gap magnitudes for spin-up and spin-down electrons, while the latter is due to that the exchange field shifts normal Fermi level at Dirac points.…”

Theoretical valley-polarized subgap transport and intravalley pairing states in a silicene-based antiferromagnet–superconductor junction

“…N Kσ > N K ′ σ , leading to the AF-induced valley polarization in silicene. This differs from the ferromagnetic exchange field or off-resonant light, which generates spin polarization in silicene [39,40]. When an electric field is also applied in the AF region, the spin degeneracy for the K and/or K ′ valleys is lifted, giving rise to the spin polarization in silicene.…”

“…In this paper, we propose a silicene-based AF/homo-or bulk-SC junction to study the valley-polarized subgap transport. The antiferromagnetic exchange field λ AF itself can induce valley polarization in silicene without the aid of an electric field, unlike the ferromagnetic exchange field or light field only generating spin polarization [39,40]. It is shown that, for a large λ AF , the Andreev-resonant peak at gap edge is supplanted by broadened features for the homo-SC model whereas by a sharp conductance dip for the bulk-SC model.…”

“…The zero-bias conductance G(0) at P v = 1 comes from the intravalley AR induced by valley-mixing scattering, which is termed the valley-triplet conductance. Here, the perfect valley-polarized intravalley pairing process can be achieved by the proximity-induced antiferromagnetism without the aid of an electric field, unlike such pairing states in [39][40][41] that require both the external electric field and light field (or ferromagnetic exchange field) in silicene.…”

“…The intravalley AR stems from the valley-mixing scattering at the interface, where the incident electron and reflected hole come from the same valley. Although the intravalley AR process has been studied in silicene/SC junctions [39,40], it needs an external electric field in silicene. In the present structure, the valley-polarized intravalley pairing process including the perfect one can be achieved by the proximity-induced antiferromagnetism without an electric field.…”