Threshold interface magnetization required to induce magnetic proximity effect

Proximity-induced magnetization (PIM) has broad implications across interface-driven spintronics applications employing spin currents. We directly determine the scaling between PIM in Pt and the temperaturedependent interface magnetization in an adjacent ferromagnet (FM) using depth-resolved magnetometry. The magnetization due to PIM does not follow the generally expected linear scaling with the FM interface magnetization, as a function of temperature. Instead, it vanishes while the FM interface magnetization remains. The effective magnetic susceptibilities of heavy-metal (HM) layers are shown to give rise to the previously unexplained asymmetric PIM found in HM/FM/HM trilayers.