Multi-level domain wall memory in constricted magnetic nanowires

We report a new type of multibit per cell (MBPC) magnetic memory wherein the movement and position of domain wall (DW) can be controlled precisely using spin polarized current. Out of two investigated configurations, the one with in-plane magnetization offers faster DW motion, and hence is suitable for high-speed applications, although stability may be an issue. In contrast, stable DWs were observed in the perpendicular configuration. Furthermore, the DW position can be controlled through a sequence of pulses with different magnitudes. Controlling the DW position offers a novel MBPC magnetic memory with high performance compared to other solid state memories.