Controllable quantum valley pumping with high current in a silicene junction

Abstract

We propose an efficient scheme for the generation and control of both pure and fully polarized valley currents in a silicene-based junction, using adiabatic quantum pumping. The pure and fully polarized valley currents are induced using ferromagnetic proximity and the application of a perpendicular electric field. We show that the valley polarized current can easily be switched from valley K to valley [Formula: see text] and vice versa, simply by reversing the direction of the electric field. Thus, the valley current is controllable electrically. Compared to the methods proposed for generation of valley current by quantum pumping in graphene, which are based on inducing strain on its sheet, our method is very simple and can be easily utilized in practical applications. Also, we show that the magnitude of pumped current in a silicene-based junction is roughly one order of magnitude greater than that of graphene. In addition to valley-related currents, our pump scheme can be used on its own to generate pure and fully polarized spin currents. A comparison between weak and strong adiabatic regimes is given, and the effects of some structural parameters that can significantly affect the pumping currents and polarizations are discussed.

One-way transport in laser-illuminated bilayer graphene: A Floquet isolator

“…This includes, notably, the phenomenon called quantum pumping, the use of timedependent potentials to steer transport and obtain a dc current at zero bias or even against an external bias voltage. In the open regime [24][25][26] quantum pumping usually relies on quantum interference and has been extensively studied for both the adiabatic 24,[27][28][29][30] and non-adiabatic cases 26,[31][32][33][34] . The proposal in this paper is different from those in different aspects.…”

Electrical controllable spin pump based on a zigzag silicene nanoribbon junction

“…Luo et al [39] proposed an adiabatic topological spin and valley pump based on silicene by applying an in-plane ac electric field and a perpendicular pumping electric field, they found that the quantum pumping phenomena are mainly dependent on the strengths of the electrostatic and the ac components of the electric fields. Subsequently, Khani et al [40] reported an efficient scheme for pumping both pure valley current and fully-polarized valley current in a silicene junction, and confirmed that the current valve effect can be electrically tuned by changing the magnitudes and the directions of the pumping electric fields. The literatures [39,40] mainly focus on the quasi-infinite silicene pump around the Dirac point, however, a ZSNR spin pump with a finite width in a large energy scale has not been investigated.…”

“…Subsequently, Khani et al [40] reported an efficient scheme for pumping both pure valley current and fully-polarized valley current in a silicene junction, and confirmed that the current valve effect can be electrically tuned by changing the magnitudes and the directions of the pumping electric fields. The literatures [39,40] mainly focus on the quasi-infinite silicene pump around the Dirac point, however, a ZSNR spin pump with a finite width in a large energy scale has not been investigated. Additionally, the spin transport in the silicene quantum pump affected by the pumping frequency, the pumping phase, and the asymmetric local magnetization, etc, has less been researched.…”

“…Adiabatic quantum pumps with time-dependent (ac) electric fields can also serve as current valves to filter spin and valley polarized currents in graphene-like devices [34][35][36][37][38][39][40]. For instance, Prada et al [35] first revealed the spin pumping effect around the Dirac point of graphene.…”

Giant magnetoresistance and spin-valley polarization of Dirac fermions modulated by magnetic fields

“…14,15) Compared to graphene, silicene has significant advantage in the study of valley pseudospin. [16][17][18][19][20][21][22][23][24] In silicene, the SOI could lead to a coupling between the spin and valley degrees of freedom. Therefore, the electrically controlled spin and valley polarized current, 16) valley-spin polarization in the magneto-optical response, 17) topological spin and valley pumping, 19,20) and the valley-locked thermospin effect 21) in silicene are demonstrated.…”