The research field called spintronics has been formed over the last 20 years or so, and has greatly developed. Since then, a number of new phenomena have been discovered, and spintronics devices that use them have been proposed. In recent years, the period between the discoveries of novel materials or new phenomena and their application and commercialization has been becoming remarkably shorter, and the importance of the fundamental understanding had become greater. This research report provides an overview of the characteristics of spintronics technologies, then summarizes the key technologies during the spintronics device development to the present, and explains about future prospects.

Highly-efficient spin injection into semiconductors is indispensable for creating viable spintronic devices, such as a spin transistor or a spin laser. In this article, we will describe our recent research activities on highly-efficient spin injection into GaAs using a half-metallic spin source of a Co-based Heusler alloy. We demonstrated clear spin injection through the observation of a nonlocal spin-valve signal and a Hanle signal. Moreover, we demonstrated dynamic nuclear polarization using electron spins injected into GaAs. The maximum spin polarization of both electron spins and nuclear spins in the GaAs channel was larger in the sample with Co₂MnSi electrodes than that in the sample with CoFe electrodes.

Spin orbit interaction in a semiconductor induces an effective magnetic field to an electron spin and offers novel functionalities for controlling the spin’s degree of freedom such as electrical spin generation and the electrical control of the spin precession. Here, we review the cutting edge of spin orbit interactions in a semiconductor heterojunction: a Stern-Gerlach spin filter and a mobile spin resonance. By spatially controlling the effective magnetic field, we can realize a spin dependent force and an oscillating effective magnetic field, which enables us to realize electrical spin generation and electron spin resonance without any external magnetic fields and magnetic materials. These results offer a new pathway to a spin source in semiconductor spintronics and for controlling quantum bits in quantum information technology.

Electrical control of magnetic properties is crucial for device applications in the field of spintronics. We demonstrated the electrical control of the ferromagnetic phase transition at room temperature in cobalt, a representative of the transition-metal ferromagnetic family. Solid-state field effect devices, consisting of an ultra-thin cobalt film covered by a dielectric layer and a gate-electrode on top of that, were fabricated for this experiment. We found that the ferromagnetic state of the film could be turned on and off isothermally and reversed simply by applying a gate voltage between the cobalt layer and the gate electrode.

Spin wave Doppler shift measurements can directly evaluate the spin polarization in current (P), which determines the performance of spintronic devices. Here we report that the Gilbert damping (α) and coefficient of the non-adiabatic spin transfer torque (β) can be simultaneously determined by performing a single series of time domain measurements of the spin wave Doppler shift in a ferromagnetic film. We will introduce a recent development in magnon spintronics.

Pure spin current without accompanying the charge current is expected to deliver the spin angular momentum efficiently compared with a spin-polarized current with a charge current. However, owing to the extremely low generation efficiency of the pure spin current, the large total power consumption is a serious obstacle for practical applications. Here, the author introduces the progress of several research efforts developed by the author’s group for the efficient control of the pure spin current; a substantial improvement of the generation efficiency of pure spin current using a highly spin polarized ferromagnet, the generation of giant pure spin current using multi-terminal spin injection and novel device structures for efficient spin ejection.

Magnetic fields often affect the dynamics and yields of photochemical reactions when radical pairs are involved as chemical intermediates. Magnetic field effects (MFEs) studies provide valuable information on the mechanisms of the chemical reactions. To investigate MFEs, we have developed bitter-type magnets to generate the ultra-high magnetic field, transient absorption spectroscopy, and numerical analysis procedures. In this article, we present the basics of MFEs and their application to the analysis of chemical reactions in nano-structured material. We also emphasize the importance of the MFEs in organic spintronics and in the development of organic devices.