Researchers from Tohoku University, University of California Riverside and Massachusetts Institute of Technology (MIT) have highlighted a series of critical achievements in antiferromagnetic spintronics (including their own contributions), revealing an emerging frontier distinguished by the coherent spin dynamics of antiferromagnets.
Within antiferromagnetic spintronics, scientists have exerted a lot of efforts on the switching and readout of static magnetic order. But coherent spin dynamics, the key to exploring the wave features of spins and integrating spintronics with quantum and neuromorphic technologies, has only received attention very recently. "The coherent spin dynamics of antiferromagnets exhibits a lot more intriguing features than that of ferromagnets," says Jiahao Han, a JSPS Research Fellow working at the Research Institute of Electrical Communication (RIEC), Tohoku University. "By harnessing this unique property, the team has been pursuing breakthroughs that eventually form a new chapter named coherent antiferromagnetic spintronics."
The team analyzed the crucial findings in coherent antiferromagnetic spintronics, including spin generation and transport, electrically driven spin rotation, and related ultrafast spintronic effects. Several important pieces of primary research in this field came from the members of this team. Cheng et al. predicted the generation of spin current from coherent spin dynamics and the picosecond magnetic switching in antiferromagnets. Liu, Han, et al. demonstrated long-distance transport of phase-correlated antiferromagnetic spin excitations. Fukami, Ohno, et al. reported current-induced chiral-spin rotation in non-collinear antiferromagnets. These discoveries lay the physical foundation for practical applications to come, such as ultrafast nonvolatile memory, ultrafast wave-based computing, and terahertz nano-oscillators.
In their article, the team suggested several research directions that may facilitate ongoing studies and fuel the future of coherent antiferromagnetic spintronics. "Whilst the spintronics community has devoted tremendous efforts to ferromagnets, there still remains a lot to do with antiferromagnets," says Shunsuke Fukami, professor at RIEC. "For example, we need to synthesize antiferromagnets with more controllable domain patterns to enhance the spin coherence. The magnetic switching process should be visualized in a time-resolved manner to guide the optimization of the operation speed. And the exploration of novel quantum effects is highly desirable for developing dissipationless communication and computing devices."
The team is optimistic that through cooperative efforts from physicists, material scientists and electrical engineers, the rapidly growing field of coherent antiferromagnetic spintronics is expected to accelerate fundamental and practical research towards efficient, ultrafast, and integrated hardware for the next-generation information technologies.