Novel Full Switching and Photo-galvanic effect in PT-invariant Quantum Antiferromagnets

About This Grant

Non-technical Abstract: The current memory technology in the commonly used hard drives is based on ferromagnetic materials that contain Cobalt or Iron. The operating speed limit for these materials is often in the gigahertz (1,000,000,000 Hz) regime. Another class of magnetic material known as antiferromagnets can support memory operation in the much higher terahertz (1,000,000,000,000 Hz) frequency. This project is to designed to realize the switching between the bit 1 and bit 0 memory states in antiferromagnets, and to measure how light converts into electric current in these two-bit states, to enable novel materials for future fast hard drives. Studying these systems will answer fundamental questions about the nature of the memory switching and the photocurrent, and enable their practical use in future faster memory and more efficient light-harvesting applications. Educational work in this project includes outreach activities on a broad introduction of quantum technology to the STEM students and to the general public. Technical Abstract: Since the discovery of giant magnetoresistance, the community has been pursuing more energy-efficient spintronic devices. Antiferromagnets are promising new pathways for developing next-generation low-dissipation technologies. Antiferromagnets, with the advantages of absence of a stray field and terahertz spin waves, are emerging as a new route to control magnetism and engineer memory devices. Antiferromagnets can have smaller independent devices to increase the storage density and faster dynamics in terahertz regime than the traditional ferromagnetic materials. Despite these promising advantages, how to directly detect and control the full switching have been challenging in the bulk materials without a canted moment. Secondly, the photocurrents in antiferromagnets have not been studied extensively due to the domain averaging effect but also exhibit new and poorly understood mechanisms. In this project the research team uses scanning second harmonic generation microcopy to directly detect antiferromagnetic full domain switching. Secondly, the research team detects the photocurrents in antiferromagnets and investigates the light-to-current conversion mechanisms. This project helps to establish the comprehensive fundamental understandings of various aspects of antiferromagnets and the domain switching mechanism and new photocurrent to establish them as new platforms for the spintronic and light-harvesting devices. In the education part, this project raises the awareness of the STEM fields involved for K-12 students. These activities include mentoring graduate and undergraduate students and performing electromagnetism demos onsite for K-12 students and the general public. 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.