Spin-torque driven self-oscillations in non-collinear coplanar antiferromagnets*

We study the spin torque driven self-oscillations in thin-film non-collinear coplanar antiferromagnets (AFMs) with spin polarization perpendicular to the plane of the film. Owing to their intrinsic THz spin dynamics, negligible stray fields, and the ability to host textures, AFMs can be used to realize various ultrafast and low-power devices including spin-torque oscillators, spin-based memories, and spin interconnects. While there are several prior reports on spin-torque-driven oscillations and switching in collinear AFMs like NiO, similar analyses in the case of planar non-collinear AFMs is currently lacking. In this work, we use a combination of micromagnetics and an effective pendulum equation to model the oscillation dynamics in chiral systems like Mn3Ir and Mn3Sn. We examine the effects of the inhomogeneous exchange interaction and the Dzyaloshinskii-Moriya interaction on the frequency and spatial distribution of AFM vectors. Our results show that THz frequency dynamics of non-collinear AFMs is similar to that of collinear AFM, however, the former has the advantage of easier detection by Anamolous Hall effect.