Conductance oscillations of a spin-orbit stripe with polarized contacts

Abstract

We investigate the linear conductance of a stripe of spin-orbit interaction in a 2D electron gas; that is, a 2D region of length ℓ along the transport direction and infinite in the transverse one in which a spin-orbit interaction of Rashba type is present. Polarization in the contacts is described by means of Zeeman fields. Our model predicts two types of conductance oscillations: Ramsauer oscillations in the minority spin transmission, when both spins can propagate, and Fano oscillations when only one spin propagates. The latter are due to the spin-orbit coupling with quasibound states of the non propagating spin. In the case of polarized contacts in antiparallel configuration Fano-like oscillations of the conductance are still made possible by the spin orbit coupling, even though no spin component is bound by the contacts. To describe these behaviors we propose a simplified model based on an ansatz wave function. In general, we find that the contribution for vanishing transverse momentum dominates and defines the conductance oscillations. Regarding the oscillations with Rashba coupling intensity, our model confirms the spin transistor behavior, but only for high degrees of polarization. Including a position dependent effective mass yields additional oscillations due to the mass jumps at the interfaces.

Thermoelectric effects in graphene with local spin-orbit interaction

“…In semiconductor quantum wires with parabolic confinement, the presence of localized Rashba interaction has been predicted to yield Fano antiresonances [20][21][22][23][24][25], to help the detection of entangled electrons [26][27][28], and to assist electron-spin resonance manipulation [29][30][31]. The effect of nonhomogeneous Rashba couplings has also been considered in the transport characteristics of two-dimensional systems [32][33][34][35][36]. A natural question is thus to what extent these results are modified in graphene monolayers.…”

Seebeck effects in two-dimensional spin transistors

“…8 shows a different type of oscillation independently of the leads' magnetic orientation. These are due to resonant Fano interference between the propagating spins and the quasibound states of opposite spins trapped between the polarized contacts [13,34]. Figure 9(b) shows that the Fano oscillations in the P case are only possible for electrons with spin s = − since for E F < 2∆ the electrons s = + are evanescent states.…”

“…At higher energies the two modes become propagating states and the Fano oscilla- tions vanish. In the AP case, the oscillations also appear for E F < 2∆ but these are now due to electrons with s = − undergoing multiple reflections between the junctions since minority electrons are inactive for transport until E F = 2∆ [34]. Figure 10 shows the thermoelectric conductance as a function of Fermi energy for both P and AP configurations.…”

Spin transistor operation driven by the Rashba spin-orbit coupling in the gated nanowire

“…In the last years, the application of the SOI to the manipulation of electron spins in semiconductor nanodevices has been a subject of numerous papers. [8][9][10][11][12][13][14][15][16][17][18][19][20][21] In Ref. 16, the conductance oscillations due to the Rashba SOI have been investigated in twodimensional stripes.…”