Over the past decades terahertz (THz) technology has been an emerging research field with a wide range of technological applications. THz radiation falls between infrared and microwave radiation in the electromagnetic spectrum and can be used for a different types of material characterization. Standard THz sources require additional lenses; they tend to break down frequently and are relatively expensive. This project explores the interaction of light and matter on ultrafast time scales and aims to develop entirely new concepts for the generation of THz radiation. These new THz sources are based on spin-electronics and are more cost effective, can provide stronger THz light, and offer additional functionalities such as the directional emission of THz light. The developed emitters could be used in many other research fields for characterization purposes, and eventually lead to new discoveries. A variety of modern technologies such as security systems, non-deconstructive evaluation techniques, as well as biological and medical applications rely on THz technologies. Therefore, the demonstration of novel, powerful THz light sources and new THz sensing schemes may have a significant impact on our society as a whole, nationwide, and around the globe.
This project explores ultrafast spin physics and introduces a paradigm shift for terahertz (THz) technologies by utilizing the superiority of devices that exploit the electrons spin rather than its charge. The studies will enable a rigorous investigation of electron-, spin- and phonon-interaction on time scales of elementary scattering events and lead to the development of completely new THz sources and sensing schemes for THz detection. The developed THz emitters might also have a significant impact on other disciplines such as material characterization, biology, medicine and telecommunication. The first phase of this project is the creation of novel types of spintronics-based THz emitters that allow for an effective way to control THz properties such as amplitude, polarization, bandwidth, and foremost, the direction of THz waves using modern nanofabrication techniques. Furthermore, the THz properties of heterostructures exhibiting topological spin textures such as magnetic skyrmions and quantum materials will be explored. The second phase focuses on the ultrafast generation of spin currents using THz light. These ultrafast spin current bunches can be used to initiate an ultrafast demagnetization process in the magnetic multilayer opening up new perspectives for all-optical magnetic recording and provide new schemes for THz detection. The time-resolved THz spectroscopy setup at Argonne National Laboratory is the ideal tool to explore this research opportunity. Additional sample characterization techniques include magneto-optical Kerr effect, Brillouin light scattering spectroscopy, magnetometry, magnetotransport and microwave spectroscopy techniques.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
