Strain control of real- and lattice-spin currents in a silicene junction

Abstract

We investigate real-and lattice-spin currents controlled by strain in a silicene-based junction, where chemical potential, perpendicular electric field and circularly polarized light are applied into the strained barrier. We find that the junction yields strain filtering effect with perfect strain control of real-(or lattice-) spin currents. (i) By applying electric field without circularly polarized light we show that total current is carried by pure lattice-spin up (or down) electrons tunable by strain. (ii) When circularly polarized light is irradiated onto silicene sheet without applying electric field, total current is carried by pure real-spin up (or down) electrons tunable by strain. High conductance peaks associated with pure real-(or lattice-) spin currents in case ii(or i) occur at specific magnitude of strain, yielding strain filtering effect. Magnitudes of filtered strain due to pure real-(or lattice-) spin currents may be tunable by varying chemical potential. Sensitivity may be enhanced by increasing thickness of strained barrier. Significantly, (iii) when both perpendicular electric field and circularly polarized light are applied, the total current is carried by three species of electron groups tunable by strain. This may lead to controllable numbers of electron species to transport. This result shows that strain filtering effect in a silicene-based junction is quite different from that in graphene junction. Our work reveals potential of silicene as a nanoelectro-mechanical device and spin-valleytronic applications.

Kétdimenziós, hexagonális szerkezetű kristályok Raman-spektrumának vizsgálata

“…Ez a kitérés a rácsra merőleges irányban azonban továbbra sem sérti meg a grafénnál talált alrács szimmetriát, vagyis a szilicén a grafénhoz hasonlóan vezető, amíg az alrács szimmetriát meg nem törjük. A kitérés azonban egyben lehetőséget ad arra, hogy ezt a szimmetriát megtörjük, hiszen például egy rácsra merőleges elektromos térrel [26; 27] vagy egytengelyű nyújtással [28][29][30][31][32] ez a szimmetria megsérthető. Ennek hatására pedig olyan tiltott sáv nyitható a szilicénben, amelyet egy külső paraméterrel könnyen változtathatunk, vagyis a rendszerben ki és bekapcsolni tudjuk a tiltott sávot, így ezt az anyagot elméletileg könnyebben lehetne integrálni az alapvetően szilícium alapú félvezetőiparba.…”

Effective Hamiltonian for silicene under arbitrary strain from multi-orbital basis

“…Using this approach, Wang et al studied the spin and valley-resolved transmission in a silicene system consisting of a number of alternating strained and unstrained segments subjected to an out-of-plane electric field 39 . The gauge potential term has also used to study the generation of spin, lattice pseudo-spin, and valley-polarized currents in strained silicene in the presence of electromagnetic barriers 40 and circularly-polarized light 41 .…”

Characterization of epitaxial silicene with Raman spectroscopy

“…The lack of an in-plane σ h mirror symmetry in the crystal, coupled with the intrinsic atomic spin-orbit coupling of Si atoms, gives rise to a topological band gap on the order of a few meV [13][14][15][16]. This band gap can be manipulated by strain [17][18][19][20], and also by an external electric field [14] which, above a critical magnitude of the electric field, induces a quantum phase transition from topological insulator to band insulator phase [14][15][16].…”