Silicene-based spin-filter device: impact of random vacancies

Abstract

Abstract.We propose a hybrid spin-filter device based on a silicene nanoribbon. A ferroelectric polymer grown on top of the nanoribbon splits spin-up and spin-down electron bands and gives rise to a spin polarisation of the conductance. In particular, we study the effects of a random distribution of vacancies on the performance of this spin-filter device. Disorder induces Anderson localisation of electrons and we find that the localisation length strongly depends on the electron spin. By adjusting the Fermi level of the source contact, only electrons with one spin orientation can reach the drain contact because their localisation length is larger than the length of the device. Electrons with opposite spin are largely back-reflected. Electric conductance then becomes spin polarised and the device behaves as a quasi-half-metal. We conclude that a moderate concentration of vacancies has little impact on the spin-filter capabilities of the device, opening the possibility to using it as a tuneable source of polarised electrons.

Spin-dependent electronic lenses based on hybrid graphene nanostructures

“…The ferromagnetic layers induce a proximity exchange splitting of the electronic states in graphene [20,21], resulting in the appearance of a spin-dependent potential profile that it is analogous to an induced Zeeman splitting of the energy levels. Similar effects are predicted to occur in silicenebased devices [22,23].…”

Spin-polarized electric current in silicene nanoribbons induced by atomic adsorption

“…Details of the calculations can be found in Ref. 26. In the linear response regime, the conductance is calculated from the transmission coefficient using the Landauer formula at zero temperature 40…”

Tuning the thermoelectric response of silicene nanoribbons with vacancies

“…We observed similar results in a previous work, where we calculated the electron localization length λ e for different vacancy concentration. 66 In the case of the total thermal conductance, the combination of the reduction of the phonon mean-free-path due to phonon-defect scattering and the Anderson electron localization (which affects the electron transmission function and consequently the electronic contribution to the thermal conductance) generate the remarkable reduction of κ total . On the other hand, due to the breaking of electron-hole symmetry and the destructive quantum interference effects within the conductor (Fano-like effect), the Seebeck coefficient displays an enhancement of the absolute maximum values as the vacancy concentration increases, as shown in Fig.…”