(a) Schematic diagram of the sample used in the experiment by injecting a spin current generation of sound waves directly.
(b) Flow due to temperature gradient
(c) Experimental photograph of the sample. Magnetic (YIG, Ni81Fe19) from platinum (Pt) and the spin current is injected into the electrode. Electromotive force is generated in the electrode.
(c) Experimental photograph of the sample. Magnetic (YIG, Ni81Fe19) from platinum (Pt) and the spin current is injected into the electrode. Electromotive force is generated in the electrode.
Professor Eiji Saitoh and Ph.D Student Ken-ichi Uchida of Tohoku University have developed a way to induce "spin current" of electrons via sound. In other words, their device generates electricity from sound waves. The concept is in the same category as Spintronics, which exploits the intrinsic spin of electrons and its associated magnetic moment.
Professor Eiji Saito explained, "[The device] consists of a piezoelectric element to produce the sound waves, a magnetic material to generate a spin current, and a three-layered metal structure to detect the spin current. By producing the sound waves, we inject a spin current from the magnetic material into the metal layers. And by using a phenomenon called the reverse spin Hall effect in the metal, we convert the spin current to an electrical voltage. In this research, we detected the spin current by measuring the voltage."
The new acoustic wave injection to generate spin current by the team allows for the extraction of electric and magnetic energy from all sorts of materials, including nonmagnetic insulators. Professor Eiji continues, "Because sound is vibration in materials, it exists everywhere in the world. By utilizing this kind of device, it might be possible to obtain spin currents and voltages from everywhere."
The Japan team, along with a group of researchers from the Technical University of Kaiserslautern in Germany, seek to find the idea material for maximum energy generation.
Up until now, Spintronic research has been in data storage as a predominant goal. It is nice to see some outside the data box work done in the field.
Eavesdropper
