Spin relaxation in a generic two-dimensional spin-orbit coupled system

Abstract

We study the relaxation of a spin density injected into a two-dimensional electron system with generic spin-orbit interactions. Our model includes the Rashba as well as linear and cubic Dresselhaus terms. We explicitly derive a general spin-charge coupled diffusion equation. Spin diffusion is characterized by just two independent dimensionless parameters: γR and γD, which control the interplay between different spin-orbit couplings. The real-time representation of the diffuson matrix (Green's function of the diffusion equation) is evaluated analytically. The diffuson describes space-time dynamics of the injected spin distribution. We explicitly study two regimes: The first regime corresponds to negligible spin-charge coupling and is characterized by standard charge diffusion decoupled from the spin dynamics. It is shown that there exist several qualitatively different dynamic behaviors of the spin density, which correspond to various domains in the (γR, γD) parameter space. We discuss in detail a few interesting phenomena such as an enhancement of the spin relaxation times, real space oscillatory dynamics, and anisotropic transport. In the second regime, we include the effects of spin-charge coupling. It is shown that the spin-charge coupling leads to an enhancement of the effective charge diffusion coefficient. We also find that in the case of strong spin-charge coupling, the relaxation rates formally become complex and the spin/charge dynamics is characterized by real time oscillations. These effects are qualitatively similar to those observed in spin-grating experiments [Weber et al., Nature 437, 1330].

Vortices in spin-orbit-coupled Bose-Einstein condensates

“…The specific laser setup used in Ref. [2] -that gives rise to an "Abelian" spin-orbit coupling (sometimes referred to as the "persistent-spin-helix symmetry point," [15][16][17][18][19][20][21] where the Rashba and Dresselhaus couplings are equal to each other) -was later analyzed in detail by Ho and collaborators in Ref. [22].…”

Tunneling-assisted spin-orbit coupling in bilayer Bose-Einstein condensates

“…There have been many proposals for generating 2D (3D) SOC for ultracold atoms [8,[38][39][40][41][42][43][44][45][46][47][48], but its experimental realization remains a challenge.…”

Infinite Spin Diffusion Length of Any Spin Polarization Along Direction Perpendicular to Effective Magnetic Field from Dresselhaus and Rashba Spin–Orbit Couplings with Identical Strengths in (001) GaAs Quantum Wells

“…4,5,6,7,8,9,10,11,12,13 For example, an infinite spin relaxation time for spin-polarization along the (110) [or (110) depending on the sign of the Rashba term] direction was predicted by Averkiev and Golub 4 in (001) GaAs quantum wells (QWs) when the cubic term of the Dresselhaus SOC is excluded, and the two leading terms, i.e., the linear Dresselhaus term and the Rashba one, are of the same strengths. With the cubic term, the spin relaxation time along the (110) direction becomes finite, but still much longer than those in the other directions.…”

“…With this term, the optimal condition is α = β − γk 2 /4 instead of α = β, 11 as predicted theoretically. 7,12 . However, the direct quantitative measurement of the largest spin diffusion length still requires further experimental efforts.…”