All-electrical perpendicular switching of chiral antiferromagnetic order

Antiferromagnets as active components in devices have been attracting attention due to their negligible stray field and ultrafast magnetic dynamics, which are promising for high-density and fast memory devices. Although the switching of antiferromagnetic (AFM) order by current-induced spin-orbit torque (SOT) has already been realized, field-free SOT-induced bidirectional switching of AFM order in perpendicular geometry has been elusive. Here we experimentally demonstrate field-free perpendicular switching of the magnetic octupole m_oct in chiral AFM Mn₃Sn by combining in-plane and out-of-plane SOTs generated by two-dimensional van der Vaals WTe₂. The out-of-plane SOT breaks the in-plane inversion symmetry and leads to deterministic bidirectional switching of m_oct in polycrystalline Mn₃Sn even without a fixed perpendicular m_oct easy axis. The switching ratio reaches up to 80% compared to 20-30% in polycrystalline Mn₃Sn and the critical current density is reduced by an order of magnitude to around 1 MA cm^-2. Our work promotes the development of chiral AFM devices toward practical application.