Understanding and Demonstration of Current-driven Ultrafast Dynamics in Antiferromagnets

Understanding and Demonstration of Current-driven Ultrafast Dynamics and Devices in Antiferromagnets Abstract

The goal of this project is to achieve an in-depth understanding of the ultrafast dynamics and devices based on new classes of antiferromagnetic (AFM) materials. These materials hold the potential to overcome the bottlenecks in speed and energy efficiency present in current technologies. The proposed research aims to set a significant milestone in next-generation information and

communication technologies by investigating the unique properties of AFMs. This research is

closely aligned with industrial needs, offering new directions that may spur further innovation and socio-economic growth. The impact is transformative, targeting the discovery of novel functional nanomaterials and new physical phenomena for high-density, high-speed, and ultra-efficient devices. Furthermore, this interdisciplinary research will have a significant educational impact, as the insights gained from spin-orbit torque engineering will offer valuable learning opportunities for students.

Individuals at various educational stages, from high school to undergraduate and graduate levels, as well as postdoctoral researchers (including women and minorities), will receive training in the interconnected and evolving fields of physical science, engineering, and computer science. This will be facilitated through the PI's involvement in outreach programs for high school and freshman students at UCLA.

Such training will help develop a diverse pool of talent skilled in scientific methodologies and practical applications. The educational benefits will be further enhanced by existing outreach initiatives at the California NanoSystems Institute and the prior NSF Engineering Research Center for Translational Applications of Nanoscale Multiferroic Systems.

Although AFM devices have the potential for ultra-high speed (picoseconds), there are major challenges in the demonstration of practical devices. Among them are lack of the understanding of switching dynamics of antiferromagnets, particularly in electrical transport measurements. Another challenge is the small readout signal due to the lack of net magnetic moment.

The proposal addresses these challenges and proposes the use of two special classes of AFM material prototypes, altermagnets and noncollinear AFM to achieve high readout for a proposed SOT device. The dynamics of the AFM materials will be studied with a time-resolved quadratic magneto-optical Kerr effect (TR-QMOKE) since AFM usually does not have a noticeable readout in linear MOKE.

To explore the antiferromagnetic dynamics excited by SOT, the combination of the state-of-the-art TR-QMOKE measurements with the innovative electrical readout for speed beyond 100 GHz will be used. In the later stage, the prototype SOT devices will be studied further with coplanar circuits integrated with high-speed CMOS. The expected outcomes of this research are the comprehensive understanding of the ultrafast current-driven dynamics in antiferromagnets and the demonstration of novel antiferromagnetic material/highly efficient spin-orbit coupling (SOC) device structures for next-generation ultra-fast (>100 GHz) antiferromagnetic spintronic applications. Detailed proposed tasks for realizing the objective are included.

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.