Interplay between resonant tunneling and spin precession oscillations in all-electric all-semiconductor spin transistors

Abstract

We investigate the transmission properties of a spin transistor coupled to two quantum point contacts acting as spin injector and detector. In the Fabry-Perot regime, transport is mediated by quasibound states formed between tunnel barriers. Interestingly, the spin-orbit interaction of the Rashba type can be tuned in such a way that nonuniform spin-orbit fields can point along distinct directions in different points of the sample. We discuss both spin-conserving and spin-flipping transitions as the spin-orbit angle of orientation increases from parallel to antiparallel configurations. Spin precession oscillations are clearly seen as a function of the length of the central channel. Remarkably, we find that these oscillations combine with the Fabry-Perot motion giving rise to quasiperiodic transmissions in the purely one-dimensional case. Furthermore, we consider the more realistic case of a finite width in the transverse direction and find that the coherent oscillations become deteriorated for moderate values of the spin-orbit strength. Our results then determine the precise role of the spin-orbit intersubband coupling potential in the Fabry-Perot-Datta-Das intermixed oscillations.

Spin filtering via resonant reflection of relativistic surface states

“…These methods are, however, not directly applicable to scattering of surface states because of a complicated structure of the incident and reflected waves in the asymptotic (unperturbed) region. Therefore, scattering of surface states has been considered either within a tight-binding scheme [8] or within a k • p theory combined with continuity conditions for the envelope function [9][10][11][12] (see also the application to spin dependent transport in nanowires [13,14]). However, in the k • p method the smoothness of the envelope spinor function generally conflicts with current conservation [15], which leads to a qualitatively incorrect separation of the probability current into the spin-orbit and classical-momentum contributions [16].…”

Spin-Selective Resonant Tunneling Induced by Rashba Spin-Orbit Interaction in Semiconductor Nanowire

“…This is two orders of magnitude faster than the spin decoherence time in InSb material (about 34 ns). The entire procedure is all-electrical and all-semiconductor [16,43] with voltages oscillating with single GHz frequencies and amplitudes below 1 V used to induce the Rashba coupling. This all makes our proposal particularly suitable for scalability purposes.…”

“…Another family of spin initialization and manipulation methods exploit the electric field induced Rashba spinorbit interaction (RSOI), that couples the electron spin with the momentum [12,13]. Modulation of this coupling allows to control the operation of spintronic devices [14][15][16]. Its sudden changes can be used to set an electron in motion in the spin-dependent direction [17,18], but also to initialize its spin all-electrically [19][20][21].…”

“…Several recent studies suggest that spin-orbit effect can be exploited for realization of spin-polarization via resonant tunneling without the need of an external magnetic fields neither application of ferromagnetic materials. Such spindependent electron tunneling through a semiconductor barrier is caused by the Rashba [16,[22][23][24][25][26] and/or the Dresselhaus [27][28][29][30][31][32][33][34][35] spin-orbit effect present at the barrier region. Unfortunately these propositions usually do not provide fidelity better than 90 %.…”

Spin filtering effect generated by the inter-subband spin-orbit coupling in the bilayer nanowire with the quantum point contact

“…The full explanation has been given by the further studies, which have shown that the predicted weak spin filter effect 17 can be strengthened by the electron-electron interaction leading to the nearly 100 % spin polarization in the regime of the single-mode transport 13 . QPCs with the SO interaction have been successfully used as the spin injector and detector in the recent experimental realization of the spin transistor 20,21 , in which about 10 5 times greater conductance oscillations have been observed as compared to the conventional spin-field effect transistor based on ferromagnets 22,23 .…”