Effect of spin-orbit couplings in graphene with and without potential modulation

Abstract

We investigate the effect of Rashba and intrinsic spin-orbit couplings on the electronic properties and spin configurations of Dirac fermions confined in: (i) a flat graphene sheet, (ii) a graphene wire with p-n-p structure, and (iii) a superlattice of graphene wires. The interplay between the spin-orbit interaction mechanisms breaks the electron-hole symmetry and the spin configuration induced by Rashba spin-orbit coupling lacks inversion symmetry in k space. We show that the Rashba spin-orbit interaction doubles the Fabry-Pérot resonant modes in the transmission spectrum of a graphene wire and opens new channels for the electron transmission. Moreover, it leads to the appearance of spin split extra Dirac cones in the energy spectrum of a graphene superlattice. It is shown that the spin of the electrons and holes confined in a flat graphene sheet is always perpendicular to their motion while this is not the case for the other nanostructures.

Effects of electron–acoustic phonon interaction in the presence of spin–orbit couplings in graphene

“…[37]. Furthermore, unless one of the spin-orbit coupling parameters takes non-zero value, symmetry between spin-up and spin-down states cannot be constituted [12]. We find that, even only one of the spin-orbit couplings that take zero value, electron-phonon interaction breaks the symmetry between two spin states.…”

“…The status of energy spectrum related with spin-orbit couplings were discussed in Ref. [12] for pristine graphene in detail. In the presence of electron-phonon interaction, we define running spin-orbit coupling constants as a function of k ka = , e ph γ -for ISOC k, e ph Δ γ ( ( )) -and k , s ,…”

“…Giant RSOC of graphene may be used in potential spintronic devices, i.e., Das-Datta spin field-effect transistor [9,10], due to the symmetry breaking between up and down spin states. In the literature, there are also some recent works on spin-orbit couplings of graphene that investigate the effects on the other physical properties of graphene and graphene based nano-structures [6,8,[11][12][13][14][15][16][17][18][19][20][21][22][23][24]. It is also well-known that the phonon modes of graphene play an important role in charge carriers dynamics.…”

“…After taking inner products and converting the sums in Eq (12). into integrals over q, i.e., , where S NS 0 = is the area of the system, and the area of the unit cell is S a…”

Normal electric field enhanced light-induced polarizations and magnetic detection of valley polarization in silicene

“…In the light absorption process, at the range of photon energies that are slightly greater than the band gap, there is another key factor which specifies how much a transition could be effective in generation of polarization. The electron-hole asymmetry is a consequence the Rashba spin-orbit interaction 20 . For those transitions that take place between valence and conduction bands particle-hole asymmetry can enhance the non-equilibrium values of a given observable.…”