Suppression of the D’yakonov-Perel’ spin-relaxation mechanism for all spin components in [111] zincblende quantum wells

Abstract

We apply the D'yakonov-Perel' (DP) formalism to [111]-grown zincblende quantum wells (QWs) to compute the spin lifetimes of electrons in the two-dimensional electron gas. We account for both bulk and structural inversion asymmetry (Rashba) effects. We see that, under certain conditions, the spin splitting vanishes to first order in k, which effectively suppresses the DP spin relaxation mechanism for all spin components. We predict extended spin lifetimes as a result, giving rise to the possibility of enhanced spin storage. We also study [110]-grown QWs, where the effect of structural inversion asymmetry is to augment the spin relaxation rate of the component perpendicular to the well. We derive analytical expressions for the spin lifetime tensor and its proper axes, and see that they are dependent on the relative magnitude of the BIA-and SIA-induced splittings.

Nonlinear Rashba model and spin relaxation in quantum wells

“…[10, 11] Approximate analytical expressions based on second-or third-order perturbation theories [10,11,12] suggest that the Rashba spin splitting (RSS) is a linear function of the in-plane wave vector k . This linear Rashba model has been widely used to investigate the various spin-related properties of low-dimensional semiconductor structures, e.g., electron spin relaxation [13,14,15,16,17] and the newly discovered spin Hall effect [18,19,20,21,22,23,24]. However, recent numerical calculations [12,25,26] show that the RSS in certain semiconductor QW's deviates from the linear behavior at large k , although the underlying physics remains unclear.…”

“…For example, we find pronounced suppression of the D'yakonov-Perel' (DP) spin relaxation rate (SRR) at large electron density, in qualitative disagreement with the prediction of the linear Rashba model. [15,16] The resonant enhancement of the electron spin lifetime in [111]-oriented quantum wells [17] also exhibits qualitatively different behavior from the linear Rashba model. The values of the SRR obtained by the two models differ by up to several orders of magnitude.…”

Spin relaxation in n-type (111) GaAs quantum wells

“…(1)-(3), Cartoixà et al proposed that a peak of the spin relaxation time (SRT) in the gate-voltage dependence appears at E z ≈ 4 k 2 z 00 γ/(2 √ 3αe) in (111) GaAs quantum wells when the cubic term in Ω(k) is neglected. 21 In (111) InGaAs quantum wells, Vurgaftman and Meyer also investigated the spin relaxation, showing that the temperature affects the gate-voltage dependence of the inhomogeneous broadening strongly and hence the SRT. 22 Both investigations are based on the single-particle approach.…”

Strain-induced spin relaxation anisotropy in symmetric (001)-oriented GaAs quantum wells

“…6,7 The different contributions in general each have a different dependence on p and can be varied independently of one another by the design of the heterostructure [8][9][10] or by the application of external perturbations. [11][12][13][14] Consequently, the interplay of the contributions that make up the resultant effective magnetic field, (p) = BIA + SIA + STR , offers many possibilities for external control of the spin dynamics, including complete cancellation of one or more Cartesian components of (p). 11,12,15 Spin rotation of a polarized electron population has been directly observed under a uniform imposed drift, 7,[16][17][18] under movement by a surface acoustic wave, 19 and also for electrons at the Fermi momentum in a degenerate two-dimensional (2D) electron gas.…”

“…[11][12][13][14] Consequently, the interplay of the contributions that make up the resultant effective magnetic field, (p) = BIA + SIA + STR , offers many possibilities for external control of the spin dynamics, including complete cancellation of one or more Cartesian components of (p). 11,12,15 Spin rotation of a polarized electron population has been directly observed under a uniform imposed drift, 7,[16][17][18] under movement by a surface acoustic wave, 19 and also for electrons at the Fermi momentum in a degenerate two-dimensional (2D) electron gas. 20 The momentum-dependent spin precession is also the basis for the Dyakonov-Perel (DP) spin-dephasing mechanism; 21 due to its random thermal motion, each electron senses a rapidly fluctuating effective field, which produces small random spin rotations between scattering events and results in the spin relaxation of a thermal electron population.…”