Competing interplay between Rashba and cubic-k Dresselhaus spin-orbit interactions in spin-Hall effect

Abstract

Focusing on the interplay between the Rashba and cubic-k Dresselhaus spin-orbit interactions (SOI), we calculate the spin accumulation S-z and the spin polarizations S-i(B) at, respectively, the lateral edges and in the bulk of the two-dimensional electron gas. Their dependences on both the ratio between the Rashba and the Dresselhaus SOI coupling constants and the electron densities are studied systematically. Strong competition features in S-z are found. In the Dresselhaus-dominated regime S-z changes sign when the electron density is large enough. In the Rashba-dominated regime S-z is essentially suppressed. Most surprising is our finding that the Rashba-dominated regime occurs when alpha approximate to 2 beta, where alpha and beta are the Rashba and the effective linear-k Dresselhaus SOI coupling constants, respectively. For the spin polarizations S-i(B), the Rashba-dominated regime occurs when alpha >=beta. Our results point out that decreasing parallel to alpha parallel to leads to the restoration of the spin accumulation S-z.