Tohoku University

Tohoku University Research News of Engineering (Tune) is a biannual publication of School of Engineering (SoE), Tohoku University, Sendai, Japan. Each Tune volume provides the scientific community with the latest research results of SoE on a selected topic.


From KS Steel To Spintronics

Text by S. "Tex" POMEROY / Photographs by Masayoshi HARABUCHI

From KS Steel To Spintronics

General Introduction


Hideo OHNO
Professor and director, CSIS

Tohoku University is renowned around the world as an institution with exceptional strengths in research of materials. In particular the Department of Materials Sciences and Engineering's programs are recognized as being the best in the world. It boasts a long history, having initially started off as Japan's first metals engineering department. It is here that the study of magnetic materials was started with the establishment in 1916 of the strongest magnetic material at that time; the KS steel. And it is here that the study of today's spintronics is gathering steam. Closely related to magnetism, spin is a property of elementary particles complementing charge and mass. Spin in electrons causes a behavior of miniature bar magnets. In the first application cases, spintronics made use of charge in addition to spin of the electrons such as giant magnetoresistance (GMR). Spin has been understood and accepted in physics since the 1920s. It took nearly three-quarters of a century for commercial exploitation to be realized. The application of spintronics is one of the most promising technological fields, as in storage devices with heads in hard disc drives that harness GMR, which results from spin, realized about a decade after GMR gained general recognition. Marked data density increases were enabled upon use of said spin as well as charge of solid-state materials. Spintronics - originated from the words "spin" and "electronics" - entails both the "off " and "on" electrical charges as well as the "down" and "up" magnetic spin (of electrons) to store information, among other activities covered by ferromagnetic materials, and is classified as a discipline under "condensed matter physics." The study of spintronics also enables device makers to place more information on a single processor in a "nonvolatile" fashion. It enables realization of circuits that consume less power and yet faster and denser than circuits that utilize just charge degree of freedom of electrons. The low power consumption of integrated circuits is critical for emerging applications such as Internet-of-Things (IoT) that connect everything in the world to the Internet. Further spintronics applications in sight include highly sensitive room-temperature magnetic sensors aiming at replacing magnetic resonance imaging (MRI) currently in use, but with refrigeration. Or heat-to-electricity conversion via spin current that enables thermoelectric power generation by a thin film, even painted film. There are more to come. Why not join!