Chargeless spin current for switching and coupling of domain walls in magnetic nanowires

Abstract

The demonstration of the generation and control of a pure spin current (without net charge flow) by electric fields and/or temperature gradient has been an essential leap in the quest for low-power consumption electronics. The key issue of whether and how such a current can be utilized to drive and control information stored in magnetic domain walls (DWs) is still outstanding and is addressed here. We demonstrate that pure spin current acts on DWs in a magnetic stripe with an effective spin-transfer torque resulting in a mutual DWs separation dynamics and picosecond magnetization reversal. In addition, long-range ($\sim$ mm) antiferromagnetic DWs coupling emerges. If one DW is pinned by geometric constriction, the spin current induces a dynamical spin orbital interaction that triggers an internal electric field determined by $\vec{E} \sim \hat{e}_{x} \cdot (\vec{n}_{1} \times \vec{n}_{2})$ where $\vec{n}_{1/2}$ are the effective DWs orientations and $\hat{e}_{x} $ is their spatial separation vector. This leads to charge accumulation or persistent electric current in the wire. As DWs are routinely realizable and tuneable, the predicted effects bear genuine potential for power-saving spintronics devices.