Antiferromagnetic Oscillators Driven by Spin Currents with Arbitrary Spin Polarization Directions

Abstract

The spin Hall effect describes interconversion between charge currents and spin currents through the spin-orbit interaction. Recently, various spin-current generation mechanisms in addition to the spin Hall effect have been studied. They include the anomalous Hall effect, spin swapping, planar Hall current, and interface-generated spin current. Spin currents generated by these mechanisms carry a spin polarization whose direction differs from that originating from the bulk spin Hall effect. In this work, we theoretically and numerically investigate antiferromagnetic spin oscillations induced by a spin current carrying an arbitrary spin polarization direction. We find that the threshold current to excite antiferromagnetic oscillations shows a nonmonotonic dependence on the spin polarization direction. Moreover, we show how material parameters and imperfections affect properties of antiferromagnetic oscillators. We expect that our result will be useful for applications of antiferromagnetic oscillators and understanding antiferromagnetic spin dynamics induced by spin currents originating from various spin-current generation mechanisms.