Current-driven magnetic domain wall motion in heterostructure films

Abstract With the rise of big data, the increasing volume of information has raised significant demands on data storage technologies, presenting various challenges to current information storage solutions. Consequently, finding more efficient and higher-capacity methods for data storage has become crucial. In comparison to conventional semiconductor random access memory, magnetic random access memory (MRAM), which has been progressively developed in recent years, shows promise as a candidate for the next generation of information storage due to its notable advantages, including non-volatility, high density, stability, low power consumption, and resistance to radiation. Among the MRAM variants, spin–orbit torque magnetic random access memory (SOT-MRAM) exhibits considerable potential for advancement. Utilizing a vertical magnetized thin film structure made up of heavy metal and ferromagnetic metal, SOT-MRAM leverages the strong spin–orbit coupling effect of the heavy metal to convert the flow of charge into pure spin flow. This process also allows for the injection of spin accumulation from the interface into the adjacent magnetic layer through mechanisms such as the spin Hall effect and the Rashba effect, ultimately applying spin–orbit torque to manipulate the magnetic moment of the magnetic layer, facilitating its reversal. This paper primarily investigates the physical mechanisms underlying the motion of magnetic domain walls driven by current-induced spin–orbit moments in vertically magnetized heterostructures. Utilizing a magneto-optical Kerr microscope to observe the movement of the magnetic domain walls, the study analyzes and compares the velocity behaviors of the domain walls across different cobalt thicknesses. These investigations offer valuable design insights for applications involving track memory driven by spin–orbit moments.