Magnetoresistance due to Edge Spin Accumulation

Because of spin-orbit interaction, an electrical current is accompanied by a spin current resulting in spin accumulation near the sample edges. Due again to spin-orbit interaction this causes a small decrease of the sample resistance. An applied magnetic field will destroy the edge spin polarization leading to a positive magnetoresistance. This effect provides means to study spin accumulation by electrical measurements. The origin and the general properties of the phenomenological equations describing coupling between charge and spin currents are also discussed.

Figure 1

The geometry of the proposed experiment with a 2D sample. The direction of the magnetic field is of no importance, so long as it lies in the 2D plane. For simplicity it is assumed to be parallel to the current.

Figure 2

Normalized magnetoresistance as a function of the parameter $\Omega {\tau }_s$ for different sample widths. 1: Eq. (18) for $\lambda \gg 1$, 2: $\lambda =1.5$; 3: $\lambda =0.8$; 4: $\lambda =0.5$; 5: $\lambda =0.3$.

Figure 3

Normalized magnetoresistance as a function of the parameter $\Omega {\tau }^{*}$, where $1/{\tau }^{*}=1/{\tau }_s+1/{\tau }_d$. 1: in the limit $\lambda \gg 1$; 2: in the limit $\lambda \ll 1$. Other curves correspond to $\lambda =0.4$, 0.8, 1.2, 1.6, and 2. One can see that all curves practically coincide.