Our recent theoretical paper on “Tunable terahertz oscillation arising from Bloch-point dynamics in chiral magnets” has now been published at Physical Review Research. This work arose from a collaboration between the University of Manchester(NEST group, Skyrmionics group, and Theoretical physics group) with the ETH Zürich (Metal Physics and Technology group). This work reveals that the formation/annihilation of skyrmions will give rise to an emergent electric field with the frequency in the THz regime. The electric signal is due to the ultra-fast Bloch-point propagation, and both the amplitude and frequency can be tuned by the manipulation of Bloch-point dynamics. Our studies provide a concept of directly exploiting topological singularities which may be relevant for THz skyrmion-based electronic devices.
(Abstract) Skyrmionic textures are being extensively investigated due to the occurrence of novel topological magnetic phenomena, and their promising applications in a new generation of spintronic devices take advantage of the robust topological stability of their spin structures. The development of practical devices relies on a detailed understanding of how skyrmionic structures can be formed, transferred, detected, and annihilated. In this work our considerations go beyond static skyrmions and theoretically show that the formation/annihilation of both skyrmions and antiskyrmions is enabled by the transient creation and propagation of topological singularities (magnetic monopolelike Bloch points). Critically, our results predict that during the winding/unwinding of skyrmionic textures, the Bloch-point propagation will give rise to an emergent electric field with a substantial amplitude and in the terahertz frequency range. We also demonstrate ways for controlling Bloch-point dynamics, which directly enable the tunablility on generation of this signal, as well as its frequency and amplitude. Our studies provide a concept of directly exploiting topological singularities for terahertz skyrmion-based electronic devices.
Y. Li*, L. Pierobon, M. Charilaou, H.-B. Braun, N. R. Walet, J. F. Löffler, J. J. Miles, and C. Moutafis
Physical Review Research 2, 033006 (2020).