Antiferromagnet-based Ultrafast Magnetic Memory Devices

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Compared with existing computer memories, memories based on magnetic materials have advantages of lower power consumption and better scalability. Moreover, information is retained in magnetic memories in the absence of power supply, providing possibilities of new computing schemes. However, existing magnetic memory devices have relatively low operating speed, which greatly limits their application. In this proposal, magnetic memory devices with ultrafast writing speed (1 nanosecond) will be developed, which can potentially bring in revolutionary changes in memory and data storage industry. The realization of the ultrafast control of magnetic dynamics could also advance understanding on the properties of magnetic materials. In addition to these broad scientific impacts, this project also provides students with unique transdisciplinary training opportunities. This research project is proposed to be integrated with the educational missions, including inspiring career interest of K-12 students in science and engineering; providing undergraduate students with cutting-edge research opportunities; and preparing students for future careers through curriculum development and interdisciplinary collaboration.To realize ultrafast magnetic memories, this proposal tries to leverage the fast development of fabrication techniques on spintronic devices with the recent advancement in new magnetic materials. Particularly, antiferromagnet will be studied for realizing magnetic memories with superior speed and high storage density. Compared with regular ferromagnet, antiferromagnet has ultrafast dynamics due to the high magnetic resonance frequency. However so far the lack of efficient control and detection mechanisms in antiferromagnet has made it challenging for practical implementations of antiferromagnet in magnetic memory devices. In this proposal, the PI focuses on spintronic devices made from antiferromagnet with internally broken inversion symmetry, where the inequality of the two sub-lattices allows the generation of staggered spin orbit torque and provides the possibility for magnetic probing and manipulation. The goals of the proposed experimental efforts include quantitatively determining the writing efficiency as well as exploring and optimizing the reading mechanisms of antiferromagnet. Specifically, a unique scheme for measuring antiferromagnet spin orbit torque is proposed, through which the underlying mechanisms for antiferromagnet switching will be revealed and quantified. Moreover, the switching speed of antiferromagnet devices will also be evaluated and the limiting factors on efficient magnetic switching will be determined through the antiferromagnet domain movement experiment. Finally, a high ON/OFF ratio will be pursued through the study of tunneling anisotropy magnetoresistance, which can lead to an efficient reading mechanism for antiferromagnet devices. In overall, the proposed research activities will not only facilitate the realization of practical antiferromagnet magnetic memory devices with fast accessing time and high density, but also enhance understanding on the current induced dynamics in antiferromagnet and widen awareness of the spin charge interaction in antiferromagnetically coupled systems.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.