Deterministic switching of perpendicular magnetization using N\'eel order-engineered out-of-plane spin in a single ferromagnet

Perpendicular switching of a ferromagnet induced by spin torques is crucial for building high density spin-based memory and logic devices, where out-of-plane spin polarization ($\sigma_z$) has become a long sought-after goal for deterministic switching without assisted magnetic fields. Here we report the observation of$\sigma_z$ and resultant field-free perpendicular switching in a single ferromagnet without any spin torque generation layers, where $\sigma_z$ is achieved through the self-generated spin polarization in the ferromagnet that is engineered by the N\'eel order of an adjacent antiferromagnetic insulator. We further demonstrated that $\sigma_z$ emerges when the self-generated spin polarization is collinear with the N\'eel vector, where the spin current is reflected back to the ferromagnet, along with rotated spin polarization toward the out-of-plane direction to induce $\sigma_z$. Since no current is shunted by antiferromagnetic insulators and the N\'eel order does not rely on single-crystalline materials, these results may provide a CMOS-compatible solution for constructing energy-efficient field-free spintronic devices.