A research team led by Assistant Professor Tomohiro Koyama of the Graduate School of Engineering, the University of Tokyo, and Associate Professor Daichi Chiba of the same graduate school, said that in a material in which a thin-film magnet and a heavy metal are bonded, magnetization is generated simply by passing an electric current directly through the sample. succeeded in.It was also shown that by controlling the amount of current, it is possible to realize a single magnetic domain state in which the magnetization of the entire sample is aligned in the same direction.
In recent years, research on a magnetic memory writing method using an electric current instead of a magnetic field has been actively conducted.Especially recently, "spin-orbit torque" generated by passing an electric current through a thin film magnet / heavy metal junction system is attracting attention as a new writing technology.Spin orbit torque is the torque given to the magnetization by the spin flow generated in the direction perpendicular to the substrate when a current is passed through the sample surface in a sample in which a thin film magnet and a heavy metal are joined.
This time, the research group created a sample (Co / Pt system) in which cobalt (Co) and platinum (Pt) in a multimagnetic domain state without magnetization at room temperature were bonded.It was found that this sample is in a multimagnetic domain without net magnetization in the absence of current, but the sample is magnetized as the current flowing through the sample increases.It was also shown that a single magnetic domain structure in which the magnetizations are aligned in the same direction can be realized by controlling the amount of current flowing.
In order to magnetize a magnet, it is common sense and common sense to apply a magnetic field from the outside.However, this study shows that it can be magnetized simply by applying a current directly to the magnet instead of a magnetic field.It is said to propose a new way of using spin-orbit torque to freely control the state of magnets in the multimagnetic domain ⇔ single magnetic domain.In the future, he plans to challenge ultra-high-speed switching between multiple magnetic domains and single magnetic domains and develop the operating principle of electromagnets that operate in sub-nanoseconds.
Paper information:[Scientific Reports] Investigation of spin-orbit torque using current-induced magnetization curve (English)
