Current-Induced Magnetic Dynamics and Magnon Transport in Easy-Plane Antiferromagnets
Luqiao Liu, Department of EECS, MIT
Electrical control and detection of magnetic ordering inside antiferromagnets has attracted considerable interests, for potential advantages in operating speed and device densities over regular ferromagnets. In contrast to ferromagnets, the compensated net magnetic moment in antiferromagnets poses difficulties in understanding the magnetic dynamics and spin transport there. In this talk, I will show that by utilizing an antiferromagnetic insulator with Dzyaloshinskii-Moriya interaction, α-Fe2O3, one can get a tiny residual magnetic moment, which provides a handle for controlling and probing Néel vector dynamics. In the first effort, by using external magnetic fields as a calibration standard for current-induced magnetic dynamics, we found that the saw-tooth like switching patterns as reported before, do not necessarily correspond to real magnetic re-orientations. Through a systematic measurement, we identified the main contributions from current as being the thermally induced magnetoelastic effect [1]. In the second study, we tried to understand the magnon-mediated spin transport in this antiferromagnetic insulator. We found that while the two linearly polarized spin wave modes in an easy-plane antiferromagnet do not carry angular momentum individually, finite spin current can still propagate via their superpositions. We show that this antiferromagnet can be finally used to build a non-volatile spin current switch [2].
[1] P. Zhang, et al., Phys. Rev. Lett., 123.247206 (2019)
[2] J. Han, et al., Nature Nanotechnology 15, 563 (2020)
Bio
Luqiao Liu is an Associate Professor of Electrical Engineering at Massachusetts Institute of Technology. He received his B.S. in physics from Peking University in 2006, and Ph.D. in Applied Physics from Cornell University in 2012. He worked as a Research Staff Member at IBM Watson Research Center before joining MIT in 2015. Luqiao’s current research focuses on spintronic material and devices for memory, logic and communication applications. Luqiao Liu has received the award of McMillan Award, NSF Career Award, Air Force Young Investigator Award, Sloan Fellowship, and International Union of Pure and Applied Physics Young Scientist Award.
