Antiferromagnetic magnon spintronics

Conventional magnonic devices uses standard ferromagnetic materials and thus operates only at GHz frequencies [1]. Magnonic devices could thus strongly benefit from the integration of antiferromagnetic materials that brings the prospect of devices operating at THz frequencies. In low damping insulating antiferromagnets, uncoherent magnons can propagate spin-information over tens of micrometers [2,3]. However, the lack of symmetry breaking still makes it difficult to excite and detect efficiently coherent antiferromagnetic magnons [4].

Within the family of conventional antiferromagnets, materials with PT broken symmetries (such as canted antiferromagnets, or altermagnets) demonstrate promising prospects for the development of antiferromagnetic magnonic. Firstly, an abundant canted antiferromagnet as hematite hosts non-degenerated and non-reciprocal spin-waves with group velocities > 10 km/s which are key functionalities for the development of magnonic devices [5]. Then, the spin-dynamic of canted antiferromagnets can be efficiently detected using spin-orbit phenomena (inverse spin-Hall effect [6] or spin-Hall magnetoresistance), reaching detection efficiency as large as μV/mW. In patterned microstructures, one can combine efficient excitation and detection in a single platinum stripe and observe antiferromagnetic spin-rectification [7]. This approach enables accessing electrically not only the linear but also the nonlinear regimes of antiferromagnetic spin-dynamics. The presence of nonlinear frequency shift and voltage saturation together with linewidth broadening is associated with antiferromagnetic Suhl-like instabilities.

Finally, I will discuss the possibility to extend these approaches to the THz range and discuss how multiferroicity can open promising road towards an efficient manipulation of THz magnetization dynamics in antiferromagnets [8].