February 21, 2022
Keio University
Project Assistant Professor Takumi Funato (Spintronics Research and Development Center) of the Keio University Global Research Institute and Associate Professor Mamoru Matsuo of the Kavli Institute for Theoretical Sciences, University of Chinese Academy of Sciences, have theoretically demonstrated that an electromotive force is generated when acoustic waves are injected into a magnet, due to the magneto-rotation effect.
The magneto-rotation effect, discovered by figures such as Einstein and Barnett, is a historically significant phenomenon that demonstrates the origin of magnetism in materials to be the rotational motion of electrons, known as spin. However, the effect is very small, and its application to spintronics devices, which require the magnetic control of materials, was considered impossible. Recently, however, a method has been demonstrated to generate a spin current using the magneto-rotation effect by rotating crystal lattice points more than one billion times per second with acoustic waves called surface acoustic waves. Furthermore, while a method to convert this spin current into an electromotive force had also been discovered, it required a complex device structure that included precious metals.
Therefore, this research group constructed a theory describing the interplay among magnetization, electron spin, and lattice rotation within a single magnetic metal thin film where lattice rotation is induced by injecting surface acoustic waves, and determined that an electromotive force is generated. As this does not require precious metals or complex device structures, it is expected to significantly pave the way for applying the magneto-rotation effect to spin devices, an endeavor that has been challenging until now.
The results of this research were published in the online edition of the American Physical Society's journal, "Physical Review Letters," on February 18, 2022 (US Eastern Time).
Please see below for the full press release.