Representation of spin of a nanoscalecoustic wave Credit: Maximilian Sonner (Institute of Physics, University of Augsburg).The rolling motion of a nano-acoustic waves has been detected by researchers. This phenomenon was predicted in 1885 by Lord Rayleigh, a Nobel Prize winner and physicist. This phenomenon could be used in acoustic quantum technology or "phononic" components that control the propagation acoustic wave.Researchers from Purdue University and the University of Augsburg conducted the study. It was published in Science Advances.The team used a nanowire to force electrons onto circular paths using the spin of an acousticwave. Modern nanophysics has a lot to offer in terms of acoustic waves. They can affect both electronic and photonic systems. The electronic processing of wireless signals is ensured by the tiny micro-acoustic chips found in smartphones, tablets, and computers. Despite the wide range of uses of nano-acoustic signals, the fundamental property, spin, of the nano-acousticwave was not discovered until this study."Since Lord Rayleigh’s pioneering work it has been known that acoustic wave propagates on the surface of solids, and which exhibit a highly characteristic, elliptical rolling motion," stated Hubert Krenner, a professor of Physics who led the University of Augsburg's study and moved to the University of Mnster. "In the case nano-acoustic wave, we have now been able to observe directly this transversal spinning, which we physicists refer to as this movement."Researchers used a very fine nanowire to study the effects of lithium niobate, a piezoelectric material. The material can deform when it is subjected to an electric current. With the help of small metal electrodes, an audio wave can be created on the material.The acoustic waves generate an electrical field that is elliptically rotating and gyrating on the surface of the material. This forces electrons in nanowires to follow circular paths."So far, we knew about the phenomenon for light," stated Zubin Jacob (Purdue's Elmore Associate professor of Electrical and Computer Engineering). We have now demonstrated that this universal effect also exists in other types waves, such as sound waves, on a technologically critical platform called lithium niobate.These research results are a landmark: Transversal spin can be used to control nano-systems and transfer information.Maximilian Sonner is a Ph.D student at the Institute of Physics, University of Augsburg. "We observed electron movement in the nanowires which were made at Technical University of Munich through the light emitted from the electrons," he said.Lisa Janker, Sonner's colleague added that "we use an extremely fast stroboscope there, which enables us practically observe this movement in actual timeeven at higher frequencies up into the gigahertz range."Farhad Khosravi recently finished his Ph.D. in Jacob’s research group. He had transferred his calculations about light to the Rayleigh acoustic waves. It has been well known that sound waves and light waves share similar properties. Khosravi stated that the amount of their spin properties matches is amazing.Researchers are confident that the universal principle behind spin-physics will result in technological breakthroughs. Now, the team is attempting to link the transversal spinning of acoustic wave with that of other waves.Jacob stated, "What we should do next is to use this transversal Acoustic Spin specifically to manipulate optical quantum system or the spin of Light for example."Continue reading Controlling magnetization via surface acoustic waveInformation: Maximilian M. Sonner and co, Ultrafast electrons driven by the transverse rotation of a surface-acousticwave, Science Advances (2021). Information from Science Advances Maximilian M. Sonner and colleagues, Ultrafast electrons cycloids driven via the transverse spin a surface-acoustic waves, (2021). DOI: 10.1126/sciadv.abf7414
